It’s really not complicated. Christians have just tried to make it so for a long time.
There’s overwhelming evidence that Hitler was a staunch Christian: the man himself said:
We tolerate no one in our ranks who attacks the ideas of Christianity. Our movement is Christian.
I get annoyed when people denigrate reading or owning Mein Kampf – everyone should read it. The myths of Hitler have overshadowed the truths, and we need to learn from the truths.
His movement was one of a religious zealot taking those beliefs to extremes, which involved the decimation of another in the Abrahamic triad, as happens with alarming regularity.