Such a grand article of faith that this guy could only act alone in running amok. There is so much BS people take as a matter of course right now. One is that the entirety of Islam is hell bent on killing all non-believers. That is the ISIS party line, and you are doing their job in promoting such propaganda.
Guess what? Slaughter of non-believers was (and in many ways still is) an article of faith of Christianity as well. Its just that civil society doesn’t give such religious views the reins of government anymore