"and if you don’t live by MY interpretation of some dead guy’s beliefs, you are wrong and are worse than the enemy*

The second part is indeed a problem in the leftist space but, regarding the first part, what isn't an interpretation of some dead guy's belief? That is how the creation of new thought works you can't just magically spawn a belief system not tainted by previous ideas into existence. Not partaking in that process would be complacency which liberals certainly have a knack for.