So the Jewish religion teaches that Judaism is a race and creates the social construct of the Jewish race
But Hitler was more familiar with the Jewish religion having relatives who believed they were Jewish
Seeing how evil the Jewish religion was he sought to save Germany from that religion
He knew they would pretend to be Christian because they believed they were a race as a tenet of their religion so they could pretend to be whatever religion and subvert it
It does not matter that he had so called Jewish DNA but that he would have relatives who practiced the Jewish religion and would be familiar with it and have the opportunity to realize that it was an evil religion
If this speculation is correct which it might not be