To be Christian is simply to accept that Jesus is reall and that he is God's son and that he died for our sins. That is what makes someone Christian. So no, Hitler may have not lied. He made it very clear that he is " a German Christian". The problem was his actions, which is what he will be judged on.

If you heard a white person say: "oh, European Colonialist weren't real white people because they don't act like us", don't you think that would be utter nonsense in your head? Firstly, they identified as white. So they are white. They looked white, so they are likely white. They came from white families, so therefore, they are white. Therefore, they are white and white people, LIKE ANY OTHER GROUP, are capable of doing bad things.

So same for Hilter and his status as a Christian. Was he a good Christian, no. But does that mean he wasn't a Christian, no. Did he declare he was a Christian, yes. Do we have proof of that, yes. Therefore, he was a Christian. And therefore, Christians are capable of bad things.

Which is why, God already set up a system where not only will he judge your beliefs, but he will also judge your actions after you have repented.

Learn to accept that there are bad apples in every group.