social pressure can be incredibly effective, especially when you can make people feel like the world is empty without the impact the "inside group" you think you belong to is making.

they make people think their only choice is remain "accepted" or be cast out among filth. mormons are good at it, but the catholic church perfected it centuries before, and it isn't limited to christianity or even to religion. heck, political parties do it, too-- no law making you join a party.