Well, re such violence as terrorism, it developed largely by Christian nations in the twentieth century. It's always been around, of course. But it became the standard method of warfare. One of the pioneers of it was Winston Churchill who ordered the aerial bombing of defenceless Kurd villages in 1920. By 1942, terrorism had became the major strategy of all powers on all sides. This continued in Korea, Cambodia and Vietnam. In fact, since 1945, the largely Christian US has been the world's biggest terrorist.
Actually, there are older roots, even for the west. Western imperialism was based on the assumption that the imperialist belonged to a superior race, and were therefore justified in conquering others, and because Churchill saw the English-speaking peoples as the world's superior race, then one was justified in using any means, including terror, to kill them. Hitler was actually quite mainstream in his thinking.
