diff --git a/README.md b/README.md
index 5066dc65..b3745e02 100644
--- a/README.md
+++ b/README.md
@@ -93,31 +93,6 @@ LIQUID
 
 By using Environments, you ensure that custom tags and filters are only available in the contexts where they are needed, making your Liquid templates more robust and easier to manage. For smaller projects, a global environment is available via `Liquid::Environment.default`.
 
-### Error Modes
-
-Setting the error mode of Liquid lets you specify how strictly you want your templates to be interpreted.
-Normally the parser is very lax and will accept almost anything without error. Unfortunately this can make
-it very hard to debug and can lead to unexpected behaviour.
-
-Liquid also comes with different parsers that can be used when editing templates to give better error messages
-when templates are invalid. You can enable this new parser like this:
-
-```ruby
-Liquid::Environment.default.error_mode = :strict2 # Raises a SyntaxError when invalid syntax is used in all tags
-Liquid::Environment.default.error_mode = :strict  # Raises a SyntaxError when invalid syntax is used in some tags
-Liquid::Environment.default.error_mode = :warn    # Adds strict errors to template.errors but continues as normal
-Liquid::Environment.default.error_mode = :lax     # The default mode, accepts almost anything.
-```
-
-If you want to set the error mode only on specific templates you can pass `:error_mode` as an option to `parse`:
-```ruby
-Liquid::Template.parse(source, error_mode: :strict)
-```
-This is useful for doing things like enabling strict mode only in the theme editor.
-
-It is recommended that you enable `:strict` or `:warn` mode on new apps to stop invalid templates from being created.
-It is also recommended that you use it in the template editors of existing apps to give editors better error messages.
-
 ### Undefined variables and filters
 
 By default, the renderer doesn't raise or in any other way notify you if some variables or filters are missing, i.e. not passed to the `render` method.
diff --git a/Rakefile b/Rakefile
index 650923bf..51c22e04 100755
--- a/Rakefile
+++ b/Rakefile
@@ -33,28 +33,13 @@ task :rubocop do
   end
 end
 
-desc('runs test suite with lax, strict, and strict2 parsers')
+desc('runs test suite with strict2 parser')
 task :test do
-  ENV['LIQUID_PARSER_MODE'] = 'lax'
-  Rake::Task['base_test'].invoke
-
-  ENV['LIQUID_PARSER_MODE'] = 'strict'
-  Rake::Task['base_test'].reenable
-  Rake::Task['base_test'].invoke
-
   ENV['LIQUID_PARSER_MODE'] = 'strict2'
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
 
   if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
-    ENV['LIQUID_PARSER_MODE'] = 'lax'
-    Rake::Task['integration_test'].reenable
-    Rake::Task['integration_test'].invoke
-
-    ENV['LIQUID_PARSER_MODE'] = 'strict'
-    Rake::Task['integration_test'].reenable
-    Rake::Task['integration_test'].invoke
-
     ENV['LIQUID_PARSER_MODE'] = 'strict2'
     Rake::Task['integration_test'].reenable
     Rake::Task['integration_test'].invoke
@@ -78,23 +63,13 @@ task release: :build do
 end
 
 namespace :benchmark do
-  desc "Run the liquid benchmark with lax parsing"
-  task :lax do
-    ruby "./performance/benchmark.rb lax"
-  end
-
-  desc "Run the liquid benchmark with strict parsing"
-  task :strict do
-    ruby "./performance/benchmark.rb strict"
-  end
-
   desc "Run the liquid benchmark with strict2 parsing"
   task :strict2 do
     ruby "./performance/benchmark.rb strict2"
   end
 
-  desc "Run the liquid benchmark with lax, strict, and strict2 parsing"
-  task run: [:lax, :strict, :strict2]
+  desc "Run the liquid benchmark"
+  task run: [:strict2]
 
   desc "Run unit benchmarks"
   namespace :unit do
@@ -127,9 +102,9 @@ namespace :profile do
     ruby "./performance/profile.rb"
   end
 
-  desc "Run the liquid profile/performance coverage with strict parsing"
-  task :strict do
-    ruby "./performance/profile.rb strict"
+  desc "Run the liquid profile/performance coverage with strict2 parsing"
+  task :strict2 do
+    ruby "./performance/profile.rb strict2"
   end
 end
 
diff --git a/lib/liquid/environment.rb b/lib/liquid/environment.rb
index 100bd0bb..095b2b09 100644
--- a/lib/liquid/environment.rb
+++ b/lib/liquid/environment.rb
@@ -34,7 +34,7 @@ module Liquid
       # @param file_system The default file system that is used
       #  to load templates from.
       # @param error_mode [Symbol] The default error mode for all templates
-      #  (either :strict2, :strict, :warn, or :lax).
+      #  (:strict2).
       # @param exception_renderer [Proc] The exception renderer that is used to
       #   render exceptions.
       # @yieldparam environment [Environment] The environment instance that is being built.
@@ -75,7 +75,7 @@ module Liquid
     # @api private
     def initialize
       @tags = Tags::STANDARD_TAGS.dup
-      @error_mode = :lax
+      @error_mode = :strict2
       @strainer_template = Class.new(StrainerTemplate).tap do |klass|
         klass.add_filter(StandardFilters)
       end
diff --git a/lib/liquid/expression.rb b/lib/liquid/expression.rb
index 00c40a4c..a6644a5f 100644
--- a/lib/liquid/expression.rb
+++ b/lib/liquid/expression.rb
@@ -11,9 +11,6 @@ module Liquid
       'false' => false,
       'blank' => '',
       'empty' => '',
-      # in lax mode, minus sign can be a VariableLookup
-      # For simplicity and performace, we treat it like a literal
-      '-' => VariableLookup.parse("-", nil).freeze,
     }.freeze
 
     DOT = ".".ord
diff --git a/lib/liquid/parser_switching.rb b/lib/liquid/parser_switching.rb
index e419dc99..4b35e213 100644
--- a/lib/liquid/parser_switching.rb
+++ b/lib/liquid/parser_switching.rb
@@ -2,59 +2,12 @@
 
 module Liquid
   module ParserSwitching
-    # Do not use this.
-    #
-    # It's basically doing the same thing the {#parse_with_selected_parser},
-    # except this will try the strict parser regardless of the error mode,
-    # and fall back to the lax parser if the error mode is lax or warn,
-    # except when in strict2 mode where it uses the strict2 parser.
-    #
-    # @deprecated Use {#parse_with_selected_parser} instead.
-    def strict_parse_with_error_mode_fallback(markup)
-      return strict2_parse_with_error_context(markup) if strict2_mode?
-
-      strict_parse_with_error_context(markup)
-    rescue SyntaxError => e
-      case parse_context.error_mode
-      when :rigid
-        rigid_warn
-        raise
-      when :strict2
-        raise
-      when :strict
-        raise
-      when :warn
-        parse_context.warnings << e
-      end
-      lax_parse(markup)
-    end
-
     def parse_with_selected_parser(markup)
-      case parse_context.error_mode
-      when :rigid   then rigid_warn && strict2_parse_with_error_context(markup)
-      when :strict2 then strict2_parse_with_error_context(markup)
-      when :strict  then strict_parse_with_error_context(markup)
-      when :lax     then lax_parse(markup)
-      when :warn
-        begin
-          strict2_parse_with_error_context(markup)
-        rescue SyntaxError => e
-          parse_context.warnings << e
-          lax_parse(markup)
-        end
-      end
-    end
-
-    def strict2_mode?
-      parse_context.error_mode == :strict2 || parse_context.error_mode == :rigid
+      strict2_parse_with_error_context(markup)
     end
 
     private
 
-    def rigid_warn
-      Deprecations.warn(':rigid', ':strict2')
-    end
-
     def strict2_parse_with_error_context(markup)
       strict2_parse(markup)
     rescue SyntaxError => e
@@ -63,14 +16,6 @@ module Liquid
       raise e
     end
 
-    def strict_parse_with_error_context(markup)
-      strict_parse(markup)
-    rescue SyntaxError => e
-      e.line_number    = line_number
-      e.markup_context = markup_context(markup)
-      raise e
-    end
-
     def markup_context(markup)
       "in \"#{markup.strip}\""
     end
diff --git a/lib/liquid/tags/case.rb b/lib/liquid/tags/case.rb
index e87e402e..e14f338d 100644
--- a/lib/liquid/tags/case.rb
+++ b/lib/liquid/tags/case.rb
@@ -23,9 +23,6 @@ module Liquid
   # @liquid_syntax_keyword second_expression An expression to be rendered when the variable's value matches `second_value`.
   # @liquid_syntax_keyword third_expression An expression to be rendered when the variable's value has no match.
   class Case < Block
-    Syntax     = /(#{QuotedFragment})/o
-    WhenSyntax = /(#{QuotedFragment})(?:(?:\s+or\s+|\s*\,\s*)(#{QuotedFragment}.*))?/om
-
     attr_reader :blocks, :left
 
     def initialize(tag_name, markup, options)
@@ -92,18 +89,6 @@ module Liquid
       parser.consume(:end_of_string)
     end
 
-    def strict_parse(markup)
-      lax_parse(markup)
-    end
-
-    def lax_parse(markup)
-      if markup =~ Syntax
-        @left = parse_expression(Regexp.last_match(1))
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.case")
-      end
-    end
-
     def record_when_condition(markup)
       body = new_body
 
@@ -129,20 +114,6 @@ module Liquid
       parser.consume(:end_of_string)
     end
 
-    def parse_lax_when(markup, body)
-      while markup
-        unless markup =~ WhenSyntax
-          raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_when")
-        end
-
-        markup = Regexp.last_match(2)
-
-        block = Condition.new(@left, '==', Condition.parse_expression(parse_context, Regexp.last_match(1)))
-        block.attach(body)
-        @blocks << block
-      end
-    end
-
     def record_else_condition(markup)
       unless markup.strip.empty?
         raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_else")
diff --git a/lib/liquid/tags/cycle.rb b/lib/liquid/tags/cycle.rb
index b7d3069c..2d372cee 100644
--- a/lib/liquid/tags/cycle.rb
+++ b/lib/liquid/tags/cycle.rb
@@ -15,8 +15,6 @@ module Liquid
   # @liquid_syntax
   #   {% cycle string, string, ... %}
   class Cycle < Tag
-    SimpleSyntax = /\A#{QuotedFragment}+/o
-    NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
     UNNAMED_CYCLE_PATTERN = /\w+:0x\h{8}/
 
     attr_reader :variables
@@ -91,35 +89,6 @@ module Liquid
       end
     end
 
-    def strict_parse(markup)
-      lax_parse(markup)
-    end
-
-    def lax_parse(markup)
-      case markup
-      when NamedSyntax
-        @variables = variables_from_string(Regexp.last_match(2))
-        @name      = parse_expression(Regexp.last_match(1))
-        @is_named = true
-      when SimpleSyntax
-        @variables = variables_from_string(markup)
-        @name      = @variables.to_s
-        @is_named = !@name.match?(UNNAMED_CYCLE_PATTERN)
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.cycle")
-      end
-    end
-
-    def variables_from_string(markup)
-      markup.split(',').collect do |var|
-        var =~ /\s*(#{QuotedFragment})\s*/o
-        next unless Regexp.last_match(1)
-
-        var = parse_expression(Regexp.last_match(1))
-        maybe_dup_lookup(var)
-      end.compact
-    end
-
     # For backwards compatibility, whenever a lookup is used in an unnamed cycle,
     # we make it so that the @variables.to_s produces different strings for cycles
     # called with the same arguments (since @variables.to_s is used as the cycle counter key)
diff --git a/lib/liquid/tags/for.rb b/lib/liquid/tags/for.rb
index cbea85bc..4b89b797 100644
--- a/lib/liquid/tags/for.rb
+++ b/lib/liquid/tags/for.rb
@@ -25,8 +25,6 @@ module Liquid
   # @liquid_optional_param range [untyped] A custom numeric range to iterate over.
   # @liquid_optional_param reversed [untyped] Iterate in reverse order.
   class For < Block
-    Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
-
     attr_reader :collection_name, :variable_name, :limit, :from
 
     def initialize(tag_name, markup, options)
@@ -72,22 +70,7 @@ module Liquid
 
     protected
 
-    def lax_parse(markup)
-      if markup =~ Syntax
-        @variable_name   = Regexp.last_match(1)
-        collection_name  = Regexp.last_match(2)
-        @reversed        = !!Regexp.last_match(3)
-        @name            = "#{@variable_name}-#{collection_name}"
-        @collection_name = parse_expression(collection_name)
-        markup.scan(TagAttributes) do |key, value|
-          set_attribute(key, value)
-        end
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.for")
-      end
-    end
-
-    def strict_parse(markup)
+    def strict2_parse(markup)
       p = @parse_context.new_parser(markup)
       @variable_name = p.consume(:id)
       raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_in") unless p.id?('in')
@@ -111,10 +94,6 @@ module Liquid
 
     private
 
-    def strict2_parse(markup)
-      strict_parse(markup)
-    end
-
     def collection_segment(context)
       offsets = context.registers[:for] ||= {}
 
diff --git a/lib/liquid/tags/if.rb b/lib/liquid/tags/if.rb
index c423c1e8..287fe78a 100644
--- a/lib/liquid/tags/if.rb
+++ b/lib/liquid/tags/if.rb
@@ -14,10 +14,6 @@ module Liquid
   # @liquid_syntax_keyword condition The condition to evaluate.
   # @liquid_syntax_keyword expression The expression to render if the condition is met.
   class If < Block
-    Syntax                  = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
-    ExpressionsAndOperators = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QuotedFragment}|\S+)\s*)+)/o
-    BOOLEAN_OPERATORS       = %w(and or).freeze
-
     attr_reader :blocks
 
     def initialize(tag_name, markup, options)
@@ -66,10 +62,6 @@ module Liquid
 
     private
 
-    def strict2_parse(markup)
-      strict_parse(markup)
-    end
-
     def push_block(tag, markup)
       block = if tag == 'else'
         ElseCondition.new
@@ -85,27 +77,7 @@ module Liquid
       Condition.parse_expression(parse_context, markup, safe: safe)
     end
 
-    def lax_parse(markup)
-      expressions = markup.scan(ExpressionsAndOperators)
-      raise SyntaxError, options[:locale].t("errors.syntax.if") unless expressions.pop =~ Syntax
-
-      condition = Condition.new(parse_expression(Regexp.last_match(1)), Regexp.last_match(2), parse_expression(Regexp.last_match(3)))
-
-      until expressions.empty?
-        operator = expressions.pop.to_s.strip
-
-        raise SyntaxError, options[:locale].t("errors.syntax.if") unless expressions.pop.to_s =~ Syntax
-
-        new_condition = Condition.new(parse_expression(Regexp.last_match(1)), Regexp.last_match(2), parse_expression(Regexp.last_match(3)))
-        raise SyntaxError, options[:locale].t("errors.syntax.if") unless BOOLEAN_OPERATORS.include?(operator)
-        new_condition.send(operator, condition)
-        condition = new_condition
-      end
-
-      condition
-    end
-
-    def strict_parse(markup)
+    def strict2_parse(markup)
       p = @parse_context.new_parser(markup)
       condition = parse_binary_comparisons(p)
       p.consume(:end_of_string)
diff --git a/lib/liquid/tags/include.rb b/lib/liquid/tags/include.rb
index 969482d4..49bc032f 100644
--- a/lib/liquid/tags/include.rb
+++ b/lib/liquid/tags/include.rb
@@ -20,9 +20,6 @@ module Liquid
   class Include < Tag
     prepend Tag::Disableable
 
-    SYNTAX = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
-    Syntax = SYNTAX
-
     attr_reader :template_name_expr, :variable_name_expr, :attributes
 
     def initialize(tag_name, markup, options)
@@ -104,29 +101,6 @@ module Liquid
       p.consume(:end_of_string)
     end
 
-    def strict_parse(markup)
-      lax_parse(markup)
-    end
-
-    def lax_parse(markup)
-      if markup =~ SYNTAX
-        template_name = Regexp.last_match(1)
-        variable_name = Regexp.last_match(3)
-
-        @alias_name         = Regexp.last_match(5)
-        @variable_name_expr = variable_name ? parse_expression(variable_name) : nil
-        @template_name_expr = parse_expression(template_name)
-        @attributes         = {}
-
-        markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = parse_expression(value)
-        end
-
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.include")
-      end
-    end
-
     class ParseTreeVisitor < Liquid::ParseTreeVisitor
       def children
         [
diff --git a/lib/liquid/tags/render.rb b/lib/liquid/tags/render.rb
index 6e1559cc..43d0bca8 100644
--- a/lib/liquid/tags/render.rb
+++ b/lib/liquid/tags/render.rb
@@ -27,7 +27,6 @@ module Liquid
   # @liquid_syntax_keyword filename The name of the snippet to render, without the `.liquid` extension.
   class Render < Tag
     FOR = 'for'
-    SYNTAX = /(#{QuotedString}+)(\s+(with|#{FOR})\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
 
     disable_tags "include"
 
@@ -111,28 +110,6 @@ module Liquid
       p.consume(:string)
     end
 
-    def strict_parse(markup)
-      lax_parse(markup)
-    end
-
-    def lax_parse(markup)
-      raise SyntaxError, options[:locale].t("errors.syntax.render") unless markup =~ SYNTAX
-
-      template_name = Regexp.last_match(1)
-      with_or_for = Regexp.last_match(3)
-      variable_name = Regexp.last_match(4)
-
-      @alias_name = Regexp.last_match(6)
-      @variable_name_expr = variable_name ? parse_expression(variable_name) : nil
-      @template_name_expr = parse_expression(template_name)
-      @is_for_loop = (with_or_for == FOR)
-
-      @attributes = {}
-      markup.scan(TagAttributes) do |key, value|
-        @attributes[key] = parse_expression(value)
-      end
-    end
-
     class ParseTreeVisitor < Liquid::ParseTreeVisitor
       def children
         [
diff --git a/lib/liquid/tags/table_row.rb b/lib/liquid/tags/table_row.rb
index b69f9148..07c6da23 100644
--- a/lib/liquid/tags/table_row.rb
+++ b/lib/liquid/tags/table_row.rb
@@ -24,7 +24,6 @@ module Liquid
   # @liquid_optional_param offset: [number] The 1-based index to start iterating at.
   # @liquid_optional_param range [untyped] A custom numeric range to iterate over.
   class TableRow < Block
-    Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
     ALLOWED_ATTRIBUTES = ['cols', 'limit', 'offset', 'range'].freeze
 
     attr_reader :variable_name, :collection_name, :attributes
@@ -62,23 +61,6 @@ module Liquid
       p.consume(:end_of_string)
     end
 
-    def strict_parse(markup)
-      lax_parse(markup)
-    end
-
-    def lax_parse(markup)
-      if markup =~ Syntax
-        @variable_name   = Regexp.last_match(1)
-        @collection_name = parse_expression(Regexp.last_match(2))
-        @attributes      = {}
-        markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = parse_expression(value)
-        end
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.table_row")
-      end
-    end
-
     def render_to_output_buffer(context, output)
       (collection = context.evaluate(@collection_name)) || (return '')
 
diff --git a/lib/liquid/template.rb b/lib/liquid/template.rb
index b007765c..6bb03dfc 100644
--- a/lib/liquid/template.rb
+++ b/lib/liquid/template.rb
@@ -22,9 +22,6 @@ module Liquid
 
     class << self
       # Sets how strict the parser should be.
-      # :lax acts like liquid 2.5 and silently ignores malformed tags in most cases.
-      # :warn is the default and will give deprecation warnings when invalid syntax is used.
-      # :strict enforces correct syntax for most tags
       # :strict2 enforces correct syntax for all tags
       def error_mode=(mode)
         Deprecations.warn("Template.error_mode=", "Environment#error_mode=")
diff --git a/lib/liquid/variable.rb b/lib/liquid/variable.rb
index 6b5fb412..0a0ad21e 100644
--- a/lib/liquid/variable.rb
+++ b/lib/liquid/variable.rb
@@ -30,7 +30,7 @@ module Liquid
       @parse_context = parse_context
       @line_number   = parse_context.line_number
 
-      strict_parse_with_error_mode_fallback(markup)
+      parse_with_selected_parser(markup)
     end
 
     def raw
@@ -41,39 +41,6 @@ module Liquid
       "in \"{{#{markup}}}\""
     end
 
-    def lax_parse(markup)
-      @filters = []
-      return unless markup =~ MarkupWithQuotedFragment
-
-      name_markup   = Regexp.last_match(1)
-      filter_markup = Regexp.last_match(2)
-      @name         = parse_context.parse_expression(name_markup)
-      if filter_markup =~ FilterMarkupRegex
-        filters = Regexp.last_match(1).scan(FilterParser)
-        filters.each do |f|
-          next unless f =~ /\w+/
-          filtername = Regexp.last_match(0)
-          filterargs = f.scan(FilterArgsRegex).flatten
-          @filters << lax_parse_filter_expressions(filtername, filterargs)
-        end
-      end
-    end
-
-    def strict_parse(markup)
-      @filters = []
-      p = @parse_context.new_parser(markup)
-
-      return if p.look(:end_of_string)
-
-      @name = parse_context.safe_parse_expression(p)
-      while p.consume?(:pipe)
-        filtername = p.consume(:id)
-        filterargs = p.consume?(:colon) ? parse_filterargs(p) : Const::EMPTY_ARRAY
-        @filters << lax_parse_filter_expressions(filtername, filterargs)
-      end
-      p.consume(:end_of_string)
-    end
-
     def strict2_parse(markup)
       @filters = []
       p = @parse_context.new_parser(markup)
@@ -85,14 +52,6 @@ module Liquid
       p.consume(:end_of_string)
     end
 
-    def parse_filterargs(p)
-      # first argument
-      filterargs = [p.argument]
-      # followed by comma separated others
-      filterargs << p.argument while p.consume?(:comma)
-      filterargs
-    end
-
     def render(context)
       obj = context.evaluate(@name)
 
@@ -133,22 +92,6 @@ module Liquid
 
     private
 
-    def lax_parse_filter_expressions(filter_name, unparsed_args)
-      filter_args  = []
-      keyword_args = nil
-      unparsed_args.each do |a|
-        if (matches = a.match(JustTagAttributes))
-          keyword_args           ||= {}
-          keyword_args[matches[1]] = parse_context.parse_expression(matches[2])
-        else
-          filter_args << parse_context.parse_expression(a)
-        end
-      end
-      result = [filter_name, filter_args]
-      result << keyword_args if keyword_args
-      result
-    end
-
     # Surprisingly, positional and keyword arguments can be mixed.
     #
     # filter = filtername [":" filterargs?]
diff --git a/test/integration/assign_test.rb b/test/integration/assign_test.rb
index fdb6c99c..a88941ae 100644
--- a/test/integration/assign_test.rb
+++ b/test/integration/assign_test.rb
@@ -41,11 +41,10 @@ class AssignTest < Minitest::Test
 
   def test_assign_uses_error_mode
     assert_match_syntax_error(
-      "Expected dotdot but found pipe in ",
+      "Expected dotdot but found pipe",
       "{% assign foo = ('X' | downcase) %}",
-      error_mode: :strict,
+      error_mode: :rigid,
     )
-    assert_template_result("", "{% assign foo = ('X' | downcase) %}", error_mode: :lax)
   end
 
   def test_expression_with_whitespace_in_square_brackets
diff --git a/test/integration/context_test.rb b/test/integration/context_test.rb
index d230734f..db68da45 100644
--- a/test/integration/context_test.rb
+++ b/test/integration/context_test.rb
@@ -632,7 +632,7 @@ class ContextTest < Minitest::Test
   end
 
   def test_has_key_will_not_add_an_error_for_missing_keys
-    with_error_modes(:strict) do
+    with_error_modes(:rigid) do
       context = Context.new
       context.key?('unknown')
       assert_empty(context.errors)
diff --git a/test/integration/error_handling_test.rb b/test/integration/error_handling_test.rb
index 0fda83ca..9f07b1f8 100644
--- a/test/integration/error_handling_test.rb
+++ b/test/integration/error_handling_test.rb
@@ -67,20 +67,13 @@ class ErrorHandlingTest < Minitest::Test
   end
 
   def test_unrecognized_operator
-    with_error_modes(:strict) do
+    with_error_modes(:rigid) do
       assert_raises(SyntaxError) do
         Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ')
       end
     end
   end
 
-  def test_lax_unrecognized_operator
-    template = Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :lax)
-    assert_equal(' Liquid error: Unknown operator =! ', template.render)
-    assert_equal(1, template.errors.size)
-    assert_equal(Liquid::ArgumentError, template.errors.first.class)
-  end
-
   def test_with_line_numbers_adds_numbers_to_parser_errors
     source = <<~LIQUID
       foobar
@@ -104,25 +97,6 @@ class ErrorHandlingTest < Minitest::Test
     assert_match_syntax_error(/Liquid syntax error \(line 3\)/, source)
   end
 
-  def test_parsing_warn_with_line_numbers_adds_numbers_to_lexer_errors
-    template = Liquid::Template.parse(
-      '
-        foobar
-
-        {% if 1 =! 2 %}ok{% endif %}
-
-        bla
-            ',
-      error_mode: :warn,
-      line_numbers: true,
-    )
-
-    assert_equal(
-      ['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
-      template.warnings.map(&:message),
-    )
-  end
-
   def test_parsing_strict_with_line_numbers_adds_numbers_to_lexer_errors
     err = assert_raises(SyntaxError) do
       Liquid::Template.parse(
@@ -133,7 +107,7 @@ class ErrorHandlingTest < Minitest::Test
 
           bla
                 ',
-        error_mode: :strict,
+        error_mode: :rigid,
         line_numbers: true,
       )
     end
@@ -157,34 +131,16 @@ class ErrorHandlingTest < Minitest::Test
 
   def test_strict_error_messages
     err = assert_raises(SyntaxError) do
-      Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :strict)
+      Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :rigid)
     end
     assert_equal('Liquid syntax error: Unexpected character = in "1 =! 2"', err.message)
 
     err = assert_raises(SyntaxError) do
-      Liquid::Template.parse('{{%%%}}', error_mode: :strict)
+      Liquid::Template.parse('{{%%%}}', error_mode: :rigid)
     end
     assert_equal('Liquid syntax error: Unexpected character % in "{{%%%}}"', err.message)
   end
 
-  def test_warnings
-    template = Liquid::Template.parse('{% if ~~~ %}{{%%%}}{% else %}{{ hello. }}{% endif %}', error_mode: :warn)
-    assert_equal(3, template.warnings.size)
-    assert_equal('Unexpected character ~ in "~~~"', template.warnings[0].to_s(false))
-    assert_equal('Unexpected character % in "{{%%%}}"', template.warnings[1].to_s(false))
-    assert_equal('Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].to_s(false))
-    assert_equal('', template.render)
-  end
-
-  def test_warning_line_numbers
-    template = Liquid::Template.parse("{% if ~~~ %}\n{{%%%}}{% else %}\n{{ hello. }}{% endif %}", error_mode: :warn, line_numbers: true)
-    assert_equal('Liquid syntax error (line 1): Unexpected character ~ in "~~~"', template.warnings[0].message)
-    assert_equal('Liquid syntax error (line 2): Unexpected character % in "{{%%%}}"', template.warnings[1].message)
-    assert_equal('Liquid syntax error (line 3): Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].message)
-    assert_equal(3, template.warnings.size)
-    assert_equal([1, 2, 3], template.warnings.map(&:line_number))
-  end
-
   # Liquid should not catch Exceptions that are not subclasses of StandardError, like Interrupt and NoMemoryError
   def test_exceptions_propagate
     assert_raises(Exception) do
diff --git a/test/integration/expression_test.rb b/test/integration/expression_test.rb
index ae84fa36..988f1d12 100644
--- a/test/integration/expression_test.rb
+++ b/test/integration/expression_test.rb
@@ -27,11 +27,6 @@ class ExpressionTest < Minitest::Test
     assert_template_result("-17.42", "{{ -17.42 }}")
     assert_template_result("2.5", "{{ 2.5 }}")
 
-    with_error_modes(:lax) do
-      assert_expression_result(0.0, "0.....5")
-      assert_expression_result(0.0, "-0..1")
-    end
-
     assert_expression_result(1.5, "1.5")
 
     # this is a unfortunate quirky behavior of Liquid
@@ -56,19 +51,6 @@ class ExpressionTest < Minitest::Test
     )
   end
 
-  def test_quirky_negative_sign_expression_markup
-    result = Expression.parse("-", nil)
-    assert(result.is_a?(VariableLookup))
-    assert_equal("-", result.name)
-
-    # for this template, the expression markup is "-"
-    assert_template_result(
-      "",
-      "{{ - 'theme.css' - }}",
-      error_mode: :lax,
-    )
-  end
-
   def test_expression_cache
     skip("Liquid-C does not support Expression caching") if defined?(Liquid::C) && Liquid::C.enabled
 
diff --git a/test/integration/parsing_quirks_test.rb b/test/integration/parsing_quirks_test.rb
index b82ce86c..52351209 100644
--- a/test/integration/parsing_quirks_test.rb
+++ b/test/integration/parsing_quirks_test.rb
@@ -31,18 +31,14 @@ class ParsingQuirksTest < Minitest::Test
   def test_error_on_empty_filter
     assert(Template.parse("{{test}}"))
 
-    with_error_modes(:lax) do
-      assert(Template.parse("{{|test}}"))
-    end
-
-    with_error_modes(:strict) do
-      assert_raises(SyntaxError) { Template.parse("{{|test}}") }
-      assert_raises(SyntaxError) { Template.parse("{{test |a|b|}}") }
+    with_error_modes(:rigid) do
+      assert_raises(Liquid::SyntaxError) { Template.parse("{{|test}}") }
+      assert_raises(Liquid::SyntaxError) { Template.parse("{{test |a|b|}}") }
     end
   end
 
   def test_meaningless_parens_error
-    with_error_modes(:strict) do
+    with_error_modes(:rigid) do
       assert_raises(SyntaxError) do
         markup = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
@@ -51,7 +47,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_unexpected_characters_syntax_error
-    with_error_modes(:strict) do
+    with_error_modes(:rigid) do
       assert_raises(SyntaxError) do
         markup = "true && false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
@@ -63,61 +59,12 @@ class ParsingQuirksTest < Minitest::Test
     end
   end
 
-  def test_no_error_on_lax_empty_filter
-    assert(Template.parse("{{test |a|b|}}", error_mode: :lax))
-    assert(Template.parse("{{test}}", error_mode: :lax))
-    assert(Template.parse("{{|test|}}", error_mode: :lax))
-  end
-
-  def test_meaningless_parens_lax
-    with_error_modes(:lax) do
-      assigns = { 'b' => 'bar', 'c' => 'baz' }
-      markup  = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
-      assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}", assigns)
-    end
-  end
-
-  def test_unexpected_characters_silently_eat_logic_lax
-    with_error_modes(:lax) do
-      markup = "true && false"
-      assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}")
-      markup = "false || true"
-      assert_template_result('', "{% if #{markup} %} YES {% endif %}")
-    end
-  end
-
   def test_raise_on_invalid_tag_delimiter
     assert_raises(Liquid::SyntaxError) do
       Template.new.parse('{% end %}')
     end
   end
 
-  def test_unanchored_filter_arguments
-    with_error_modes(:lax) do
-      assert_template_result('hi', "{{ 'hi there' | split$$$:' ' | first }}")
-
-      assert_template_result('x', "{{ 'X' | downcase) }}")
-
-      # After the messed up quotes a filter without parameters (reverse) should work
-      # but one with parameters (remove) shouldn't be detected.
-      assert_template_result('here',  "{{ 'hi there' | split:\"t\"\" | reverse | first}}")
-      assert_template_result('hi ', "{{ 'hi there' | split:\"t\"\" | remove:\"i\" | first}}")
-    end
-  end
-
-  def test_invalid_variables_work
-    with_error_modes(:lax) do
-      assert_template_result('bar', "{% assign 123foo = 'bar' %}{{ 123foo }}")
-      assert_template_result('123', "{% assign 123 = 'bar' %}{{ 123 }}")
-    end
-  end
-
-  def test_extra_dots_in_ranges
-    with_error_modes(:lax) do
-      assert_template_result('12345', "{% for i in (1...5) %}{{ i }}{% endfor %}")
-    end
-  end
-
   def test_blank_variable_markup
     assert_template_result('', "{{}}")
   end
@@ -131,24 +78,4 @@ class ParsingQuirksTest < Minitest::Test
   def test_contains_in_id
     assert_template_result(' YES ', '{% if containsallshipments == true %} YES {% endif %}', { 'containsallshipments' => true })
   end
-
-  def test_incomplete_expression
-    with_error_modes(:lax) do
-      assert_template_result("false", "{{ false - }}")
-      assert_template_result("false", "{{ false > }}")
-      assert_template_result("false", "{{ false < }}")
-      assert_template_result("false", "{{ false = }}")
-      assert_template_result("false", "{{ false ! }}")
-      assert_template_result("false", "{{ false 1 }}")
-      assert_template_result("false", "{{ false a }}")
-
-      assert_template_result("false", "{% liquid assign foo = false -\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false >\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false <\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false =\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false !\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false 1\n%}{{ foo }}")
-      assert_template_result("false", "{% liquid assign foo = false a\n%}{{ foo }}")
-    end
-  end
 end # ParsingQuirksTest
diff --git a/test/integration/tags/cycle_tag_test.rb b/test/integration/tags/cycle_tag_test.rb
index dfb5984d..cf3fdea1 100644
--- a/test/integration/tags/cycle_tag_test.rb
+++ b/test/integration/tags/cycle_tag_test.rb
@@ -96,11 +96,6 @@ class CycleTagTest < Minitest::Test
     template1 = "{% assign 5 = 'b' %}{% cycle .5, .4 %}"
     template2 = "{% cycle .5: 'a', 'b' %}"
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("b", template1)
-      assert_template_result("a", template2)
-    end
-
     with_error_modes(:strict2) do
       error1 = assert_raises(Liquid::SyntaxError) { Template.parse(template1) }
       error2 = assert_raises(Liquid::SyntaxError) { Template.parse(template2) }
@@ -121,14 +116,6 @@ class CycleTagTest < Minitest::Test
     template4 = "#{assignments}{% cycle n  e: 'a', 'b', 'c' %}"
     template5 = "#{assignments}{% cycle n  e  'a', 'b', 'c' %}"
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("a", template1)
-      assert_template_result("a", template2)
-      assert_template_result("a", template3)
-      assert_template_result("N", template4)
-      assert_template_result("N", template5)
-    end
-
     with_error_modes(:strict2) do
       error1 = assert_raises(Liquid::SyntaxError) { Template.parse(template1) }
       error2 = assert_raises(Liquid::SyntaxError) { Template.parse(template2) }
@@ -153,10 +140,6 @@ class CycleTagTest < Minitest::Test
       {% endfor %}
     LIQUID
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
@@ -170,10 +153,6 @@ class CycleTagTest < Minitest::Test
       {% endfor %}
     LIQUID
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
diff --git a/test/integration/tags/include_tag_test.rb b/test/integration/tags/include_tag_test.rb
index 44c0dcda..e35addcd 100644
--- a/test/integration/tags/include_tag_test.rb
+++ b/test/integration/tags/include_tag_test.rb
@@ -205,14 +205,6 @@ class IncludeTagTest < Minitest::Test
   end
 
   def test_strict2_parsing_errors
-    with_error_modes(:lax, :strict) do
-      assert_template_result(
-        'hello value1 value2',
-        '{% include "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
-        partials: { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' },
-      )
-    end
-
     with_error_modes(:strict2) do
       assert_syntax_error(
         '{% include "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
@@ -301,16 +293,10 @@ class IncludeTagTest < Minitest::Test
     env = Liquid::Environment.build(file_system: TestFileSystem.new)
 
     assert_raises(Liquid::SyntaxError) do
-      Template.parse("{% include template %}", error_mode: :strict, environment: env).render!("template" => '{{ "X" || downcase }}')
-    end
-    with_error_modes(:lax) do
-      assert_equal('x', Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: true, environment: env).render!("template" => '{{ "X" || downcase }}'))
+      Template.parse("{% include template %}", error_mode: :rigid, environment: env).render!("template" => '{{ "X" || downcase }}')
     end
     assert_raises(Liquid::SyntaxError) do
-      Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: [:locale], environment: env).render!("template" => '{{ "X" || downcase }}')
-    end
-    with_error_modes(:lax) do
-      assert_equal('x', Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: [:error_mode], environment: env).render!("template" => '{{ "X" || downcase }}'))
+      Template.parse("{% include template %}", error_mode: :rigid, include_options_blacklist: [:locale], environment: env).render!("template" => '{{ "X" || downcase }}')
     end
   end
 
@@ -404,10 +390,6 @@ class IncludeTagTest < Minitest::Test
   def test_include_template_with_invalid_expression
     template = "{% include foo=>bar %}"
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
@@ -417,10 +399,6 @@ class IncludeTagTest < Minitest::Test
   def test_include_with_invalid_expression
     template = '{% include "snippet" with foo=>bar %}'
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
@@ -430,10 +408,6 @@ class IncludeTagTest < Minitest::Test
   def test_include_attribute_with_invalid_expression
     template = '{% include "snippet", key: foo=>bar %}'
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
diff --git a/test/integration/tags/render_tag_test.rb b/test/integration/tags/render_tag_test.rb
index 0bd09d08..440342c3 100644
--- a/test/integration/tags/render_tag_test.rb
+++ b/test/integration/tags/render_tag_test.rb
@@ -106,14 +106,6 @@ class RenderTagTest < Minitest::Test
   end
 
   def test_strict2_parsing_errors
-    with_error_modes(:lax, :strict) do
-      assert_template_result(
-        'hello value1 value2',
-        '{% render "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
-        partials: { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' },
-      )
-    end
-
     with_error_modes(:strict2) do
       assert_syntax_error(
         '{% render "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
@@ -318,10 +310,6 @@ class RenderTagTest < Minitest::Test
   def test_render_with_invalid_expression
     template = '{% render "snippet" with foo=>bar %}'
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
@@ -331,10 +319,6 @@ class RenderTagTest < Minitest::Test
   def test_render_attribute_with_invalid_expression
     template = '{% render "snippet", key: foo=>bar %}'
 
-    with_error_modes(:lax, :strict) do
-      refute_nil(Template.parse(template))
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
diff --git a/test/integration/tags/table_row_test.rb b/test/integration/tags/table_row_test.rb
index 45628ce9..e8f7adb4 100644
--- a/test/integration/tags/table_row_test.rb
+++ b/test/integration/tags/table_row_test.rb
@@ -188,29 +188,6 @@ class TableRowTest < Minitest::Test
     assert_template_result(expected_output, template)
   end
 
-  def test_table_row_renders_correct_error_message_for_invalid_parameters
-    assert_template_result(
-      "Liquid error (line 1): invalid integer",
-      '{% tablerow n in (1...10) limit:true %} {{n}} {% endtablerow %}',
-      error_mode: :warn,
-      render_errors: true,
-    )
-
-    assert_template_result(
-      "Liquid error (line 1): invalid integer",
-      '{% tablerow n in (1...10) offset:true %} {{n}} {% endtablerow %}',
-      error_mode: :warn,
-      render_errors: true,
-    )
-
-    assert_template_result(
-      "Liquid error (line 1): invalid integer",
-      '{% tablerow n in (1...10) cols:true %} {{n}} {% endtablerow %}',
-      render_errors: true,
-      error_mode: :warn,
-    )
-  end
-
   def test_table_row_handles_interrupts
     assert_template_result(
       "<tr class=\"row1\">\n<td class=\"col1\"> 1 </td></tr>\n",
@@ -439,10 +416,6 @@ class TableRowTest < Minitest::Test
       <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td><td class="col4">4</td><td class="col5">5</td></tr>
     OUTPUT
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result(expected, template)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(SyntaxError) { Template.parse(template) }
       assert_match(/Invalid attribute 'invalid_attr'/, error.message)
@@ -452,14 +425,6 @@ class TableRowTest < Minitest::Test
   def test_tablerow_with_invalid_expression_strict_vs_strict2
     template = '{% tablerow i in (1..5) limit: foo=>bar %}{{ i }}{% endtablerow %}'
 
-    with_error_modes(:lax, :strict) do
-      expected = <<~OUTPUT
-        <tr class="row1">
-        </tr>
-      OUTPUT
-      assert_template_result(expected, template)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(SyntaxError) { Template.parse(template) }
       assert_match(/Unexpected character =/, error.message)
diff --git a/test/integration/template_test.rb b/test/integration/template_test.rb
index c01c7161..ed86b3f9 100644
--- a/test/integration/template_test.rb
+++ b/test/integration/template_test.rb
@@ -259,7 +259,7 @@ class TemplateTest < Minitest::Test
   end
 
   def test_nil_value_does_not_raise
-    t      = Template.parse("some{{x}}thing", error_mode: :strict)
+    t      = Template.parse("some{{x}}thing", error_mode: :rigid)
     result = t.render!({ 'x' => nil }, strict_variables: true)
 
     assert_equal(0, t.errors.count)
diff --git a/test/integration/variable_test.rb b/test/integration/variable_test.rb
index e272b96b..82e7ac3e 100644
--- a/test/integration/variable_test.rb
+++ b/test/integration/variable_test.rb
@@ -176,48 +176,9 @@ class VariableTest < Minitest::Test
     )
   end
 
-  def test_variable_lookup_should_not_hang_with_invalid_syntax
-    Timeout.timeout(1) do
-      assert_template_result(
-        'bar',
-        "{{['foo'}}",
-        {
-          'foo' => 'bar',
-        },
-        error_mode: :lax,
-      )
-    end
-
-    very_long_key = "1234567890" * 100
-
-    template_list = [
-      "{{['#{very_long_key}']}}", # valid
-      "{{['#{very_long_key}'}}", # missing closing bracket
-      "{{[['#{very_long_key}']}}", # extra open bracket
-    ]
-
-    template_list.each do |template|
-      Timeout.timeout(1) do
-        assert_template_result(
-          'bar',
-          template,
-          {
-            very_long_key => 'bar',
-          },
-          error_mode: :lax,
-        )
-      end
-    end
-  end
-
   def test_filter_with_single_trailing_comma
     template = '{{ "hello" | append: "world", }}'
 
-    with_error_modes(:strict) do
-      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
-      assert_match(/is not a valid expression/, error.message)
-    end
-
     with_error_modes(:strict2) do
       assert_template_result('helloworld', template)
     end
@@ -226,11 +187,6 @@ class VariableTest < Minitest::Test
   def test_multiple_filters_with_trailing_commas
     template = '{{ "hello" | append: "1", | append: "2", }}'
 
-    with_error_modes(:strict) do
-      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
-      assert_match(/is not a valid expression/, error.message)
-    end
-
     with_error_modes(:strict2) do
       assert_template_result('hello12', template)
     end
@@ -239,11 +195,6 @@ class VariableTest < Minitest::Test
   def test_filter_with_colon_but_no_arguments
     template = '{{ "test" | upcase: }}'
 
-    with_error_modes(:strict) do
-      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
-      assert_match(/is not a valid expression/, error.message)
-    end
-
     with_error_modes(:strict2) do
       assert_template_result('TEST', template)
     end
@@ -252,11 +203,6 @@ class VariableTest < Minitest::Test
   def test_filter_chain_with_colon_no_args
     template = '{{ "test" | append: "x" | upcase: }}'
 
-    with_error_modes(:strict) do
-      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
-      assert_match(/is not a valid expression/, error.message)
-    end
-
     with_error_modes(:strict2) do
       assert_template_result('TESTX', template)
     end
@@ -265,11 +211,6 @@ class VariableTest < Minitest::Test
   def test_combining_trailing_comma_and_empty_args
     template = '{{ "test" | append: "x", | upcase: }}'
 
-    with_error_modes(:strict) do
-      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
-      assert_match(/is not a valid expression/, error.message)
-    end
-
     with_error_modes(:strict2) do
       assert_template_result('TESTX', template)
     end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index a6d3e16e..201bdf26 100755
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -8,7 +8,7 @@ $LOAD_PATH.unshift(File.join(File.expand_path(__dir__), '..', 'lib'))
 require 'liquid.rb'
 require 'liquid/profiler'
 
-mode = :strict
+mode = :rigid
 if (env_mode = ENV['LIQUID_PARSER_MODE'])
   puts "-- #{env_mode.upcase} ERROR MODE"
   mode = env_mode.to_sym
diff --git a/test/unit/condition_unit_test.rb b/test/unit/condition_unit_test.rb
index d7f35f60..67d6e262 100644
--- a/test/unit/condition_unit_test.rb
+++ b/test/unit/condition_unit_test.rb
@@ -167,9 +167,9 @@ class ConditionUnitTest < Minitest::Test
   end
 
   def test_parse_expression_in_strict_mode
-    environment = Environment.build(error_mode: :strict)
+    environment = Environment.build(error_mode: :rigid)
     parse_context = ParseContext.new(environment: environment)
-    result = Condition.parse_expression(parse_context, 'product.title')
+    result = Condition.parse_expression(parse_context, 'product.title', safe: true)
 
     assert_instance_of(VariableLookup, result)
     assert_equal('product', result.name)
diff --git a/test/unit/parse_context_unit_test.rb b/test/unit/parse_context_unit_test.rb
index f53cd114..d1b32efc 100644
--- a/test/unit/parse_context_unit_test.rb
+++ b/test/unit/parse_context_unit_test.rb
@@ -38,12 +38,6 @@ class ParseContextUnitTest < Minitest::Test
   end
 
   def test_parse_expression_with_variable_lookup
-    result_strict = strict_parse_context.parse_expression('product.title')
-
-    assert_instance_of(VariableLookup, result_strict)
-    assert_equal('product', result_strict.name)
-    assert_equal(['title'], result_strict.lookups)
-
     error = assert_raises(Liquid::InternalError) do
       strict2_parse_context.parse_expression('product.title')
     end
@@ -66,9 +60,6 @@ class ParseContextUnitTest < Minitest::Test
   end
 
   def test_parse_expression_with_empty_string
-    result_strict = strict_parse_context.parse_expression('')
-    assert_nil(result_strict)
-
     error = assert_raises(Liquid::InternalError) do
       strict2_parse_context.parse_expression('')
     end
@@ -77,9 +68,6 @@ class ParseContextUnitTest < Minitest::Test
   end
 
   def test_parse_expression_with_empty_string_and_safe_true
-    result_strict = strict_parse_context.parse_expression('', safe: true)
-    assert_nil(result_strict)
-
     result_strict2 = strict2_parse_context.parse_expression('', safe: true)
     assert_nil(result_strict2)
   end
@@ -109,12 +97,6 @@ class ParseContextUnitTest < Minitest::Test
 
   private
 
-  def strict_parse_context
-    @strict_parse_context ||= ParseContext.new(
-      environment: Environment.build(error_mode: :strict),
-    )
-  end
-
   def strict2_parse_context
     @strict2_parse_context ||= ParseContext.new(
       environment: Environment.build(error_mode: :strict2),
diff --git a/test/unit/partial_cache_unit_test.rb b/test/unit/partial_cache_unit_test.rb
index 623241b4..72555d52 100644
--- a/test/unit/partial_cache_unit_test.rb
+++ b/test/unit/partial_cache_unit_test.rb
@@ -184,7 +184,7 @@ class PartialCacheUnitTest < Minitest::Test
       },
     )
 
-    [:lax, :warn, :strict, :strict2].each do |error_mode|
+    [:strict2].each do |error_mode|
       Liquid::PartialCache.load(
         'my_partial',
         context: context,
@@ -193,7 +193,7 @@ class PartialCacheUnitTest < Minitest::Test
     end
 
     assert_equal(
-      ["my_partial:lax", "my_partial:warn", "my_partial:strict", "my_partial:strict2"],
+      ["my_partial:strict2"],
       context.registers[:cached_partials].keys,
     )
   end
diff --git a/test/unit/tags/case_tag_unit_test.rb b/test/unit/tags/case_tag_unit_test.rb
index 11458db8..b7c562ba 100644
--- a/test/unit/tags/case_tag_unit_test.rb
+++ b/test/unit/tags/case_tag_unit_test.rb
@@ -20,10 +20,6 @@ class CaseTagUnitTest < Minitest::Test
       {%- endcase -%}
     LIQUID
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("one", template)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
 
@@ -41,10 +37,6 @@ class CaseTagUnitTest < Minitest::Test
       {%- endcase -%}
     LIQUID
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("one", template)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
 
@@ -62,7 +54,7 @@ class CaseTagUnitTest < Minitest::Test
       {%- endcase -%}
     LIQUID
 
-    with_error_modes(:lax, :strict, :strict2) do
+    with_error_modes(:strict2) do
       assert_template_result("one", template)
     end
   end
@@ -77,7 +69,7 @@ class CaseTagUnitTest < Minitest::Test
       {%- endcase -%}
     LIQUID
 
-    with_error_modes(:lax, :strict, :strict2) do
+    with_error_modes(:strict2) do
       assert_template_result("one", template)
     end
   end
@@ -113,10 +105,6 @@ class CaseTagUnitTest < Minitest::Test
     LIQUID
     assigns = { 'foo' => { 'bar' => 'baz' } }
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("one", template, assigns)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
 
@@ -135,10 +123,6 @@ class CaseTagUnitTest < Minitest::Test
     LIQUID
     assigns = { 'foo' => { 'bar' => 'baz' } }
 
-    with_error_modes(:lax, :strict) do
-      assert_template_result("one", template, assigns)
-    end
-
     with_error_modes(:strict2) do
       error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
 
diff --git a/test/unit/variable_unit_test.rb b/test/unit/variable_unit_test.rb
index 03f5862a..590aa3f3 100644
--- a/test/unit/variable_unit_test.rb
+++ b/test/unit/variable_unit_test.rb
@@ -72,12 +72,6 @@ class VariableUnitTest < Minitest::Test
     assert_equal([['replace', ['foo', 'bar']], ['textileze', []]], var.filters)
   end
 
-  def test_symbol
-    var = create_variable("http://disney.com/logo.gif | image: 'med' ", error_mode: :lax)
-    assert_equal(VariableLookup.new('http://disney.com/logo.gif'), var.name)
-    assert_equal([['image', ['med']]], var.filters)
-  end
-
   def test_string_to_filter
     var = create_variable("'http://disney.com/logo.gif' | image: 'med' ")
     assert_equal('http://disney.com/logo.gif', var.name)
@@ -108,7 +102,7 @@ class VariableUnitTest < Minitest::Test
     assert_equal(VariableLookup.new('foo-bar'), create_variable('foo-bar').name)
     assert_equal(VariableLookup.new('foo-bar-2'), create_variable('foo-bar-2').name)
 
-    with_error_modes(:strict) do
+    with_error_modes(:strict2) do
       assert_raises(Liquid::SyntaxError) { create_variable('foo - bar') }
       assert_raises(Liquid::SyntaxError) { create_variable('-foo') }
       assert_raises(Liquid::SyntaxError) { create_variable('2foo') }
@@ -131,36 +125,6 @@ class VariableUnitTest < Minitest::Test
     assert_equal([['things', [], { 'greeting' => 'world', 'farewell' => 'goodbye' }]], var.filters)
   end
 
-  def test_lax_filter_argument_parsing
-    var = create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ), error_mode: :lax)
-    assert_equal(VariableLookup.new('number_of_comments'), var.name)
-    assert_equal([['pluralize', ['comment', 'comments']]], var.filters)
-
-    # missing does not throws error
-    create_variable(%(n | f1: ,), error_mode: :lax)
-    create_variable(%(n | f1: ,| f2), error_mode: :lax)
-
-    # arg does not require colon, but ignores args :O, also ignores first kwarg since it splits on ':'
-    var = create_variable(%(n | f1 1 | f2 k1: v1), error_mode: :lax)
-    assert_equal([['f1', []], ['f2', [VariableLookup.new('v1')]]], var.filters)
-
-    # positional and kwargs parsing
-    var = create_variable(%(n | filter: 1, 2, 3 | filter2: k1: 1, k2: 2), error_mode: :lax)
-    assert_equal([['filter', [1, 2, 3]], ['filter2', [], { "k1" => 1, "k2" => 2 }]], var.filters)
-
-    # positional and kwargs intermixed (pos1, key1: val1, pos2)
-    var = create_variable(%(n | link_to: class: "black", "https://example.com", title: "title"), error_mode: :lax)
-    assert_equal([['link_to', ["https://example.com"], { "class" => "black", "title" => "title" }]], var.filters)
-  end
-
-  def test_strict_filter_argument_parsing
-    with_error_modes(:strict) do
-      assert_raises(SyntaxError) do
-        create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ))
-      end
-    end
-  end
-
   def test_strict2_filter_argument_parsing
     with_error_modes(:strict2) do
       # optional colon