Without the strictures and traditions imposed by a religion that promises to punish sinners, the moral controls that moderate our base desires will lose their validity, leading ultimately to moral chaos.
So you can't be moral without religion? Comparing the ethics and morals of most athiests I know to those with a religious belief, I find the non-religious are usually more concerned with the welfare of their fellow man. You know, all that "do unto others" stuff.
Just because you would happily rob, rape and kill if not for religion telling you that's a nono doesn't mean others would.
YMMV