It is not hard to imagine why people might hate. It is hard to imagine how they might stop hating.

If these people won, and all of the people they hate so much died tomorrow, would they stop killing? I think not. I suspect that they would begin killing other sects of their own religion, and after that people who don't adhere closely enough to the rules of the "one true religion".

Murderers want to murder. In the end, the reasons are made up long after the decision to murder is made.

Can they be rehabilitated in some way?