When I was a professor at Georgia State University in Atlanta, I required my students to read Nazi theology. I wanted them to understand how some Christians bent the words of the Bible into weapons aimed at Jews, and how those weapons found their mark in the concentration camps. My Christian students responded to these disturbing readings with one disturbing voice. The Nazis were not Christians, they said. Jesus was, after all, a Jew. This response was in many respects laudable. But in distancing their religion from the history of the Holocaust, my students absolved themselves of any responsibility for reckoning with how their religious tradition might have contributed to these horrors.I think we do this with much of Christian history, not just the Nazi Holocaust. We hide the parts we disagree with, clean out the dark spots, and say to ourselves, "they weren't really Christians". We see only the "good" side of our faith, but not the "bad", and we don't really learn from our faith's mistakes.
Prothero mentioned to me that it was the book Theologians Under Hitler: Gerhard Kittel, Paul Althaus and Emanuel Hirsch, by Robert P. Ericksen, that he assigned to his students.