Lately I've noticed that it's become popular for atheists to assert that Hitler was a Christian. This is just ludicrous...
Check out this short documentary (12 min) that shows the truth about Hitler and that he was anything but a Christian.
If Hitler was a Christian he certainly was not a true christian - to which atheists often cry, "No True Scotsman fallacy (NTS) - aha - you are wrong because you've committed a logical fallacy!"
This is absolute nonsense and shows that the atheist doesn't understand this particular logical fallacy. There is absolutely no intersection between Hitler and what a true Christian is - so the sets are mutually exclusive and the NTS fallacy does not apply. (See http://www.tektonics.org/guest/scotty.htm for a fuller explanation of the NTS fallacy.)
The fact that atheists are so keen to distance themselves from Hitler (who was an unbeliever) is because they know in their hearts that absolute morality exists, and that Hitler was absolutely wrong in what he did. Absolute morality and calling anyone's actions wrong or evil make no sense in an atheistic worldview - who cares what one evolved animal does to other evolved animals? Who cares what one bunch of chemicals does to another bunch of chemicals? A bunch of chemical reactions just fizz and can't be called right or wrong. They just are. That's the absurdity of the atheistic worldview. I've actually had some atheists who were consistent with their worldview tell me that they didn't believe what Hitler did in killing millions of people was wrong.
No, Hitler was absolutely morally wrong in what he did. And God will bring justice to him, and all the other murderous dictators that have killed and murdered others and acted sinfully in rejection of God and rebelled against His command for us to love each other.