I'm not sure that religion reigns anyone in. It isn't structured that way from my understanding, leaving too much to interpretation by the leaders. In my experience, exceptionally racist and activist folks are also religious, and use their chosen religion to support and motivate their actions and beliefs. You're right in that people who are good followers of whatever will be more pacifist (you didn't say that exactly but I think that is what you were at), but there aren't that many folks who get deep into scripture. In many religions.