I have noticed a curious phenomenon. We have large numbers of fervent theists who relentlessly push this idea associating atheists with Nazis and mass-murdering communists — I understand there was a movie with that premise, I've seen Kennedy's 'documentary' that reveled in that claim, and of course the frauds at the Discovery Institute have a pseudo-history book that accuses Darwinists of being genocidal maniacs — but there's also an odd bias in the apologists for religion. If an atheist should point out that these evil behaviors are not unique to atheists, that religions have also supported genocidal maniacs (for instance, a certain pope in WWII who turned a blind eye to atrocities), or if we rebut those odious arguments by pointing out that Hitler and most of the Nazis were Catholic, not atheists, suddenly we are accused of playing the Nazi card. It doesn't matter that no one is claiming that all religious people are Nazis, just bringing up the uncomfortable realities that undermine the accusations against us makes us guilty of Godwinning an argument.
Yeah, I'm looking at you, Nick Matzke. Trying to make a false equivalence between the nasty claims of theists and creationists, and the academic replies of atheists, is rather sleazy.