Christopher Hitchens on why freedom of speech includes hate speech.
Thomas Jefferson: "Ridicule is he only weapon which can be used against unintelligible propositions."
Well, not the ONLY weapon, but ridicule can be effective, and if done well, entertaining.
Respecting other people's RIGHT to their opinion in no way supposes that you are obliged to respect the actual opinions, although it is generally a good idea to remember that everyone has feelings. Save the combative stance for the appropriate circumstance.