Communist Russia fell because of an inherent flaw in Communism, not because they didn't believe in God. And are you really, really arguing that Christianity hasn't done things far worse than Communist Russia? What about the Crusades (and "chivalry" in general)? How about the Catholic Church's policy of non-involvement during the Holocaust? What about one of the things listed as a cause for the Protestant Reformation: the selling of indulgences (basically, paying money to the Church to be able to sin)? And don't forget, some of the first people to leave for America did so because of the religious intolerance and bigotry of Christians. Oh, and those Westboro folk I'm sure everyone here loves so much are also Christian. Oh, and since your knowledge of history seems so limited, there was one other empire in recent years that was very strongly Christian. They were known as the National Socialists, or the Nazis, and they were very, very strongly Christian. As were all of the Axis powers in WW2 (excluding the USSR, which, I might add, became an Allied power once betrayed by their Christian ally).
The point isn't that Christians are bad people because for the most part, they're not. The point is that there are good and bad people in any group and that pointing out one failure associated with atheism does not make any atheist philosophy an automatic failure. Don't just cherry pick one or two things from history to justify your position.