Julian Baggini is certainly right that being an atheist does not necessarily mean being an associate of the holocaust. Still, in order to defend atheism from the accusation of having been the cause of mass murders in the 20th century, Baggini seems to go very far:

[R]eligion is by nature not only divisive, but divisive in a way which elevates some people above others. It is not too fancicul, I think, to see how the centuries of religious tradition in Western society made possible the kind of distinction between the superior Aryans and the inferior others which Nazism required. (Baggini, Atheism, 2003, p. 86)

If Baggini is right, any thought implying distinctions (such as Plato’s utopian Republic) would lead to this kind of effect. And supporters of Christianity could claim that they were the ones who said that we are all children of God… Again, I am led to think that putting the history of atheism in a wider context, e.g., taking India and China into the picture would help enhancing the debate.