Presently we associate religious murders with the Muslim faith, e. g. ISIS, and that record speaks for itself in modern times, but in the Crusades Christian King Richard of England killed as many Muslims in one day as died on 9/11. (They were his prisoners, and he didn't want to let them go and didn't have the food to feed them so mass murder seemed the "Christian" thing to do.) The Jewish scriptures are filled with bloody tales, all doubtlessly myths, of slaughters of whole villages, men, women, children, and babies. When people start taking thousands of years old mythical literally, it leads to murder.
Arguably, a right amount of religious is a good things. Undeniably, too much religion is disastrous. Among the latter are knife wielding fanatics and television evangelists saying the fall of the Stock Market is because of family planning. The former is a murder of people; the latter is a poisoner of intelligent thinking.