I see it as most see people see other organizations they join; to be with like minded individuals. If you believe in Christianity it is nice to have a place where the teachings can be taught, and understood. Same goes further for Methodist, Baptist, Catholithc, etc.

The herd menality is everywhere you go. It is more prevalent in religion due to the impact religion has on the world as a whole. Same as the extremist theory. People, individuals may I add, will go on the deep end to defend what THEY believe and not realize the trouble they cause.