You act like taking away religion leaves the door swinging wide for unspeakable evil. My point is simply that evil gets in anyway; a loony is a loony, wherever he goes on Sunday morning.
Would the Inquisitors have killed fewer if they had assault rifles? Would the Crusaders have killed fewer if they'd had tanks? Did the US, with its Christian leaders, ideals, and soldiers, kill fewer Native Americans as it expanded westward? Did the US, with its Christian leaders, ideals, and soldiers, kill fewer civilians during World War II for the sake of what it held dear?