Colors are the deeds and sufferings of light.
~ Johann Wolfgang von Goethe
While liberals are leery of religious fundamentalism in general, they consistently imagine that all religions at their core teach the same thing and teach it equally well. This is one of the many delusions borne of political correctness.
The secular argument, or the liberal argument, is to as much as possible remove taboos so things do not become unmentionable; to let some air into the discussion.