"Probably the only person who had any chance of hampering him (Hitler) was the Pope, who had the ear of 40 million German Catholics, but he barely said a word. When German forces occupied Rome, he opened his sanctuaries to give refuge to many thousands of non-Aryans, but he was committed to neutrality in his search for peace and feared provoking Hitler, so he opened not his mouth.
As their armies liberated the death camps of eastern Europe, the allies realised what a good cause they had been fighting in. But the fact that 6 million Jews had been systematically killed left the church with some terrible questions. Where had God been? Can the omnipotent watch the most unthinkable atrocities in the history of inhumanity without lifting a finger? Then again, where had the church been? For all that some individual Christians did, the church as a whole did disgracefully little to stop the Holocaust. In fact, was it not positively responsible?"
Source: A Short History of Christianity by Stephen Tomkins