Almost all of them committing these atrocities for religious reasons. The Chinese government has treated Tibetan Buddhists horribly for decades, but you don't see any Tibetan Buddhist suicide bombers. There have been some sects of Buddhism in the past that have done horrible things, but in general it's harder to become a Buddhist suicide bomber than it is to become a Muslim suicide bomber. Some religions condemn violence of any kind. For example, I doubt anyone could be a Jainist suicide bomber.

If you don't believe me, hear it from the horse's mouth. Here is a video from a Muslim peace conference in Norway: http://www.youtube.com/watch?v=bV710c1dgpU#t=45s It will take five minutes of your time, but I think it shows best how sincere these people are.