My two cents on this very complex topic, probably lacking an enormous amount of sophistication, is that religion is an excuse to form separate tribes and attack those who threaten another's resources, land and security, even if the threat merely exists their heads. The idea that a divine power bequeaths power to one group over another is used, time and again, to assert claims that they are somehow more deserving of rights than the other tribe. It builds justification for one's deeds, but if religion didn't exist than it would still be present just in another form, such as nationalism and race. Pretty bleak, huh?