Why are most of terrorist muslims?

Let me tell u why! if u study Quran u will see it's written that "You kill the "KAFARAN"(the people who don't believe in god). this is just an example from what is written in Quran about terrors. The people who teror are real muslims and believe that the person that they are going to kill is against muslims, so he/she is against islam so he/she is against god, so he/she doesn't believe in god because if he does, he woud be a muslim, so not against the muslim!