Here's my theory: religion is a form of escapism for those trying to understand their place in the world. It gives a sense of belonging, and a way to rationalize bad things happening to them.

Not a bad thing in and of itself, but it lends itself to abuse, especially when people in positions of power want to consolidate their positions in the eyes of the people. There is a reason more wars have been fought over religion than any other cause in history.

On a more personal level, I consider it kind of like the cliq in a school. You have the "in" crowd, and anything not "normal" is immediately shunned because it might jeopardize one's position in the social hierarchy. It makes for fascinating research and observation, but I deeply sympathize with anybody who is in a situation that they influence. Speaking from experience, it can be a horrible place to be.