Most terrorists are Islamic. That's just a fact. According to Forbes, there are only four major groups who have been responsible for the majority of the terroristic activities during the past three years. The Islamic State is indeed the world's deadliest terrorist group in the world during this time. Ironically, most of the attacks have been carried out in Nigeria and not in some of the areas we hear more about, like Europe. Why are the attacts mostly Islamic?
They are on a mission to wage war on those they are opposed to and who oppose them and their religion. To them, that is actually part of their religion, to rid the world of the infidel. Bombings and other terroristic attacts are their way of waging the war. So, that means that most of the terrorists in the world today are Islamic. That is what they do to get their message across and to stand for what they believe in, unfortunately.