Because christians have an incredibly long and well-documented history of hating and exterminating whole communities of jews. I gave a morbidly long, but hardly complete list of these events back upthread a ways, if you want to track down the specifics.
I was just wondering why anyone would think Hitler being a hypocrute would be significant. The imporant thing is not what he believed personally, but what he preached. He didn't personally kill millions of Jews. His audience did.