The claim that nonbelievers share a kinship with some of the greatest evils of the 20th century has become a regular feature of just about every religious debate. Like weeds pushing through cracked cement, the claim is persistent, resilient, and everywhere.
It's also completely valid.
We atheists do share at least our atheism in common with these infamous monsters. Sure, there might be some ambiguity here. But does it help us to fret over the details? We do ourselves a disservice when we point to, say, evidence that Hitler wasn't really an atheist. We imply that it matters whether Hitler was an atheist, when we should be arguing the opposite.
Even if we take the claim to be true, isn't it an unfair comparison? Isn't it like drawing genocidal inferences from mustaches simply because Hitler wore one? No it isn't, because we atheists define ourselves by our atheism. If someone implied that mustaches were the key to peace on Earth, then an objection of "well, Hitler wore a moustache, and look how that worked out" would be as fair as it would be compelling.
"Look," says the theist. "Religion provides a framework for morality. Atheists want to replace this framework with something else. What else? Atheists don't say. Such a moral vacuum could be filled by anything. Historically, alternatives to religious morality have frequently involved genocidal evils so monstrous as to dwarf even the most heinous crimes of the faithful. This concerns me."
Read that argument again, and notice where the theist takes his sharp turn down the slippery slope to Auschwitz: "What else? Atheists don't say."
There's the rub. That's where I think they've got us.
Atheism is a negative term. It says nothing about what we are, what we believe, only about what we don't believe. An atheist, defined as such, is amoral in a way that no religious person could ever be. This is why a Christian would rather vote for a Muslim than for an atheist: Even if she disagrees with Islam, at least she has some idea of the basis of the Islamic moral code. At least she knows the Muslim has a moral code!
Atheism, on the other hand, has nothing to say on the subject, and this is what the "Argument From Hitler" is all about: The Argument From Hitler reveals the fallacy we commit whenever we pretend that "atheism" has moral content. It does not. There is no atheist morality as such. The Argument From Hitler reveals this to be so by reminding us that such an "atheist morality" would have to be shared by Hitler, Mao and Jodie Foster alike. They are all atheists, after all. To distinguish them by reference to some standard that isn't contained within the definition of "atheism" is to play a round of "No True Scotsman."
In a debate, the fallacy presents itself whenever the atheist discusses morality without first defining himself as something other than an atheist. Enter the Argument From Hitler to undermine the only apparent basis for the atheist's moral statements, his atheism. This leaves the atheist fumbling awkwardly for something other than atheism to distinguish himself from Stalin, a basis for his morality other than the atheism he shares with Pol Pot. This is a painful struggle to watch, and it's made no less painful when the atheist wrongly blames the Argument From Hitler itself as the problem. It's not: In this, its proper context, the Argument From Hitler is a rational, valuable and important tool in our opponents' arsenal. If the atheist has no defense other than to describe yet more things he doesn't believe in ("I'm not a fascist, or a communist, or a Christian!"), then the theist is understandably left with the perception that an empty hole stands in the place of the atheist's morality. Hell, I'm left with that perception. Until we atheists find something to fill that hole, we shouldn't even trust ourselves when we say that today's atheists have nothing in common with the genocidal tyrants of yesteryear.
This worries a lot of people, to say the least. It is this worry that drives them to compare us to Hitler. Seen in this light, the comparison is not a cheap shot, deserving of only a sneering dismissal. It is their justified fear of a "worst case scenario" with a proven historical track record that, by our own admission, is in complete harmony with the word we have chosen to define our community: ATHEIST.
I blame ourselves for this mess. We've defined ourselves by an intellectual nonentity for long enough. We did it because it was easier than reaching consensus on a positive identity, and because it remains the most efficient means of distinguishing ourselves from the religious masses. But it's an intellectual and epistemological black hole, for which we are now seeing the consequences.
So. Forget for the moment the political or diplomatic ramifications of using the word "atheist," which are being discussed at length elsewhere. We should be asking ourselves whether maintaining this identity is morally and logically defensible. From where I stand, all this poison fruit strikes me as evidence of a real and intractable problem at the root of "atheism-as-identity."
I definitely don't think the problem is going to be solved by changing our name. We need to stop pretending that atheism is anything but silent on issues of morality. When the debate turns to moral issues, atheists should announce this to be the case, remove their atheist hat, and put on their "secularist" hat, their "humanist" hat, their "sociologist" hat, or their "rationalist" hat. Let theists try to argue that Hitler was a humanist, if they can, and then let the humanists defend humanism on its own terms.
When we are clear and unequivocal about the nonexistence of "atheist morality," when atheist speakers respond to moral questions with the same sort of befuddled "what does that have to do with atheism?" we'd expect of auto mechanics, we will see the end of the Argument From Hitler.