To throw in for scientologists, more than scientology... it isn't without effect...

The power of it isn't in truths about alien overlords, but in the fact that they use working religious and psychological techniques. They make you confess your deepest darkest secrets to them with a lie detector, they have confession. They focus on moral improvements, and teach psychological and social techniques that change the way that people see and interact with you. They teach people to be more assertive, and kindly dominating, and self-confidence.

I'm by no means suggesting that scientology is in any sense good or true, but that scientologists don't fall into it because its stories are so compelling, but because of what it does for them in the practice of it.