I think the aspect of the indoctrination that kept me mentally imprisoned for so long was the notion that you can't trust yourself. Usually they're pretty subtle about this, but sometimes they're pretty up front about it. So while it's not the most overused scripture, it's certainly up there:
Jeremiah 17:9
The heart is more treacherous than anything else and is desperate. Who can know it?
Feeling like your life would be better outside the cult? It's just your treacherous, desperate heart fooling you.