Ever notice the self-defense mechanisms in Christianity? They're in the Bible, actually. Not just made up, like some things.

Here are some, off the top of my head:
Lean not on your own understanding. Something doesn't make sense to you? Forget about it. Just believe it anyway. You don't have to understand.
Can't understand some things.
God's ways are not our ways. Sure, this is probably quite true, but its usefulness in protecting a set of beliefs is immeasurable: it allows for anything --
literally -- to be accepted, including stories about atrocities committed by God's followers (by his orders) or by God himself, and nobody can complain. It gives infinite freedom to make up stories about God, including "God told me to ______" with
literally anything in the blank. "Give you $50." "Sacrifice my son." "Marry you." "Kill you."
anything.
If anyone preaches a different gospel than the ones we preach, let them be accursed. Man. This one comes in really handy, in the realm of sect-vs-sect strategies.
Heaven and hell! Once you believe these things exist, and you will go to one of the other in the forever-afterlife, and you can't leave the faith or you'll go to hell, well, talk about self-preservation! (Of the dogma, I mean!)