See, the way that you disavow Hitler as a Christian is the same way that Muslims disavow terrorists. Neither are true representations for what the respective religions stand for. There is ample evidence in Hitler's writings that show he relied on some form of religious foundation for his plans. He believed he was doing God's work after all.
Muslims terrorists are not really Muslims, by the same argument you used to disavow Hitler.
Hitler said that he was doing what he did, in the name of God. I defy you to find a quote of Stalin or Mao saying that they were going to kill millions of people because of atheism. They do seem to have set up a religion of state. Lenin was put on display like a shrine post-mortem (IIRC). So if anything, religion is responsible for Hitler, Mao, Stalin, N. Korea, etc.