In my experience, it's from biblical ignorance. Then when you enlighten them, they would rather reject the truth of the Bible than their ideology.
James 4:4 You adulterous people, don't you know that friendship with the world is hatred toward God? Anyone who chooses to be a friend of the world becomes an enemy of God.
Oh, I've seen it go beyond Biblical ignorance. I'm aware of an ELCA pastor slamming a Bible on the floor and state to his Bible class that it's just another book and shouldn't be taken literally. That's not Biblical ignorance; that's Biblical rejection, from one who should know better...