"A Christian nation, rounding up Jews to beat them up, seize their property, and ultimately killing them in the biggest mass-murder ever - because of their religion. (Nazi Germany)"
Don't lay that at Christianity's feet. Read your history. Nazism was steeped in paganism and the cult of the ancient teutonic warrior, all based upon a foundation of racial purity. The Nazis slaughtered a hell of a lot of Christians, too: It wasn't just the Jews who were sent to the camps (although there is no doubt that the Nazis reserved their deepest hatred for the Jews). The Nazis were more athiest than anything else, and if they adhered to any religious beliefs, they were similar in nature to the neo-paganism of today's American Left (Gaia worship, etc.).
I don't lay this at Christianity's feet. But the Nazis didn't come out of nowhere, and neither did their imitaors in occupied France.
Israeli officials always pointed out that while there were many Christian Justs that helped Jews escape death, there were many others who helped the Nazis. Hence the special relation Israel always had with Germany. Hence Israel's insistence of having France apologize for its particpation in the Holocaust.
All in all, I think that's fair and square. The Nazis weren't Christians, even some of their imitators in occupied countries dared call themselves as such. WHat happened in occupied Europe was not in any way linked to the Christian faith of dogmas. And indeed there were Christians who rose against Nazi tyranny - and who were sent to death camps of were decapitated for that.
But there were many others who did nothing, and said little more. To me - and I'm in no way pretending everybody should agree with that - it's like the Good Samaritan parabole, where the Levite - whose name suggests he's most keen on obeying Lord's words - turns away from the exhausted traveler.