christianity V.S. islam

There's one thing I have never understood about religion, for the most part they all support goodwill toward men, not to go out of your way to harm others and so on and so forth for the most part.. Not to commit evil upon each other yet here we are having mass casualties on both ends if god is good why would most of these attacks Muslims make against us be in his name or visa versa. It just doesn't make sense i find more sense in xenon's theory of movement being an illusion anyone have anything to say?