Once again, killing someone is against the commandments (or however they're called in the Koran) of the Muslims/Islam believers. It's the fanatic idea that makes them go mad, by someone telling them to go angry against [...] for getting a shitload of virgin women in afterlife... it's just the same as you could tell a Christan that he'd get 50 bucks from you if he beats the fuck out of his classmate - the action itself has nothing to do with the religion, aside from being against the 'rules', the executers just get blinded by the gain they're promised, so please don't confuse this with the religion itself.