By positing a spiritual force of evil being behind Hitler’s actions, you raise the question of “why does god allow evil”. Greater minds than mine have wrestled with this problem and failed to come up with a satisfactory answer. The usual recourse is “free will”, but frankly that is an abdication of responsibility. God just couldn’t be bothered to stop Hitler. Another is “it’s all part of God’s plan”. Equally pathetic, what sort of evil entity has a plan that requires the death of millions? Well, Hitler, obviously. And God. Which makes God just as responsible. He could give humans free will and still stop them from doing evil things, or at least preventing the consequences for others. Not doing so when you are able is itself evil, arguably more evil than the original perpetrator.

Treating each other as Christ would implies knowledge of what Christ would do. As much of that is pure invention by that supreme self-publicist Paul, it is dubious at best. Really, the church should be called the Paulian church not the Christian church as so much of Christian belief seems to have been concocted out of whole cloth by Paul, how many times does he write something like “Christ would want X” with absolutely no evidence. “Be excellent to each other” is far more meaningful.