Although denny may have a point in Nazi Germany, I think in communist Russia an atheist regime was greatly at fault. And I think it's important to recognize that just as Christains should recognize the atrocities of their past. It's important to recognize that no ideology Christanity, atheism, muslim or whatever is free of blame. We must all work towards assuring murders aren't in the name of any ideology.
The problem with the labeling of "religion of peace" from Christians or athiests is the same, it comes from a very two faced place. Instead, recognize that there are groups within the muslim world that are disgusting but also hold up the mirror and realize we come from such a disgusting past too. Condemn all who act so evil and feel pride that the Christains and atheists seem to be learning their lesson (not that they don't kill but that they don't do it in the name of their ideology as much) and becoming people's that are beginning to pride themselves on being better then they once were. This is a bad thing to argue over, which side was more atrocious because there is more than enough blame to go around. Accept the past and vow never to let it happen again.