First, let's clarify a theological issue. While we are saved by faith in Jesus alone, we are not saved by a faith that is alone. A genuine Christian faith works. A true Christian will have good works and while still sinning will not have a life marked by gross sin for extended periods of time.

A good tree will bear good fruit. A bad tree will produce bad fruit. The Nazis were very bad fruit coming from a bad tree.

Historically speaking, it should be noted the Nazis were no fans of Christianity. The Nazis recognized the Jewish roots of Christianity and hated it.