Again, I'd like to see the evidence, from "Mein Kampf" or wherever. (Sounds like the "Christian Identity" philosophy.)
If Hitler really thought that, it could just show what a crackpot he was, like most Leftists. It probably shows that he (being a canny, deceptive politician) felt he had to accommodate his ideology to the fact that Germany had been Christian for centuries, and many Germans still were believers. So he had to do something to distract the people from the obvious fact that Jesus was a Jew.
The Nazis really didn't like Christianity, considering it a weakling's belief system, and profoundly contradictory of their racial and eugenic beliefs.
Or it could mean he believed in a warped version of Christianity, one that speaks to his depravity.
I see no evidence he didn't believe what he said.