Religion exists for reasons on individual and community level.

Reasons on individual level:
-a need to simplify complexity of life
-a need to find purpose of one's existance
-a need to rationalise bad things happening to a person

Reasons on communiy level:
-a way to control believers: socially, morally, economically, politically
-that's it really

I have observed this in believers and their leaders over and over again.