Given the incidence of m murders by deranged Muslims, can we conclude that religion is not a factor?

We've had a few m murders by deranged atheists (Columbine, Oklahoma City, Virginia Tech), and perhaps one by a deranged Christian (Eric Rudolf), but thousands by deranged Muslims (the 9-11 attacks, untold homicide bombings in the Middle East, and now 13 dead and 30 wounded at Fort Hood). The politically correct answer is that these m killings have nothing to do with religion. Do the relative incidence of Muslim m murders to atheist and Christian m murders support the PC consensus?