OneEyedJoe: Humans are social apes, and social pressure is quite powerful if applied correctly.
Well, according to the OP, we are not "apes," but we are actually legumes:
Half Banana: there is a large pool of ready made friends who appear to be decent welcoming human beans who will accept all-comers as long as they conform and believe the cult dogma.
It's the vine mentality that takes over. That's the root of the problem. It makes it hard for anyone to leave.
Seriously though, there is a powerful mix of social and psychological forces at work: social pressure to conform, confirmation bias, cognitive dissonance and a severe lack of critical thinking skills all combine to create an obedient and compliant drone.