Anyone who has ever watched a debate between a theist and an atheist has seen this familiar scene: 1) the atheist points out that religion, despite its claims to inform human morality, has been (and continues to be) responsible for many atrocities and moral outrages; 2) the theist counters that the greatest mass murderers in the history of mankind (usually some combination of Hitler, Stalin, Pol Pot, and Mao) were atheists; 3) the theist wins the argument (note: step 3 may or may not be completely made up). Like the sun rising in the morning, the leaves changing colour in autumn, or the Rapture happening two days ago (remember how awesome that was?), this line of argument is so predictable as to be almost laughable.
There are so many flaws with this argument that it makes the head spin, so I am going to try and walk you, the reader, through them sequentially.
Hitler, Stalin, Pol Pot and Mao were atheists
This is debatable. Leaving aside Hitler for a moment (who was baptized Catholic and used Christian religious imagery extensively as the justification for his racist political ideology), there certainly have been leaders that have killed many of their own people, many of whom were openly atheist. However, none of the people that are commonly listed (and some that are less commonly mentioned like Idi Amin, Fidel Castro, and Kim Il-Sung) left religion out of the picture. Instead of worship of a supernatural deity that speaks directly into the ear of the leader, these men simply bypassed the middle man and pronounced themselves akin to the deity.
Without exception, if you look at how these men ruled their countries, they made themselves a figurehead and object of worship. Even today, there are pictures of Castro and Guevera plastered all over Cuba. Idi Amin was Uganda and erected a quasi-religious framework around him; ditto for Stalin (but even more so). Pol Pot and Mao, arguably the closest to being truly atheistic dictators, still installed themselves as nearly-supernatural beings whose word was divine law; in the case of Kim Il-Sung this is quite literally true. Strictly speaking, this doesn’t qualify as atheism. There is a world of difference between saying “there are no gods” and “I am a god”. It exploits the seemingly-innate propensity of human beings to subjugate themselves to something – far closer to the religious position (“I speak for the gods”) than the atheist position.
But, even if that were true…
Let’s pretend for a moment that we can accurately label the above listed dictators as being atheists (in the interest, perhaps, of avoiding being inaccurately accused of using the “No True Scotsman” fallacy). The argument is still invalid because the crimes these men committed were not done in the name of atheism. Whereas theistic murderers often use religious scripture and theological ‘reasoning’ to justify why suchandsuch group of people are deserving of the end of a sword, I know of no examples where someone has said the following:
Because there are no gods, we have the right to murder/oppress this group.
Such a statement would be on par with the justifications that come from religiously-justified crimes against humanity (“God hates fags”, “Unbelievers deserve hell”, “Jews killed Jesus”). And while there have been many atrocities that have happened for non-religious reasons, it is not reasonable or consistent to classify anything that is not pro-theistic as being atheist. The statement “there are no gods” could be twisted to support the murder of people if one was particularly psychopathic, but I don’t think it ever has.
But, even if that were true…
But let’s for a moment imagine that someone unearthed such an example, where the lack of god belief was used as a justification to commit a crime against humanity. Even then, this argument would have no value, since atheism is not a morality claim. The whole purpose of raising the atrocities committed with religious justification is to poke holes in the argument that religious faith is the source of morality, or that adherence to religious codes makes humanity more moral. If this were the case, it would be a rare exception that religious fervor could be twisted to serve a genocidal purpose – people’s faith would steer them away from the clear evil of mass murder.
The fact that even ‘atheistic’ mass murderers used the trappings of religious adherence and unwavering faith to rally people to their clearly immoral cause suggests that, if anything, religion makes people less moral. At least it seems to be useful in getting people to short-circuit their critical thinking faculties and engage in behaviour that, if they were to sit and think rationally about it (or, in hindsight) they would rightly recoil from. Even so, the cup of religion overfloweth with claims of superior morality – claims not supported by the available evidence. Atheism has no such morality claims; it is simply the lack of god-belief. It is entirely incidental (or, more likely, due to a third variable like propensity for independent introspection) that atheists are less likely to murder, rape, etc.
But even if that were true…
Even if we, for the sake of argument, granted all of the above (untrue) assumptions – that atheistic dictators committed their crimes from a position of atheistic moral authority – this argument would still be completely worthless. The issue of whether or not atheism is nice has absolutely no relationship to whether or not atheism is true. Even if we were to grant that atheists are just as shitty are theists, that doesn’t say anything about which of the two positions of correct – all it says is that people suck. Making the assertions that morality comes from the divine assumes the existence of the divine. Failure to demonstrate the existence of the divine (we’re still waiting, by the way) completely invalidates the theistic moral position. Saying that theists are super-nice doesn’t mean that the gods exist any more than saying atheists are shitty people does. Both positions are entirely orthogonal to the central claim of whether or not gods are real.
In summary
I’m honestly not sure why this argument is perceived to carry any weight in a serious debate. Surely respected theists are aware of Godwin’s Law, and while I hold out no expectations for people debating issues on Reddit or on someone’s Facebook wall, I would imagine that enough people have at least thought through their position long enough to realize that such an assertion has no bearing whatsoever on their position. And yet, keep your eyes and ears open for the next big debate between an atheist and a believer – I’ll be willing to bet cookies that the rotting, shuffling corpse of this thoroughly-useless argument will rise again and attempt to devour the brains of the audience.
Remember, aim for the head.
TL/DR: People are often pointing out that some of the greatest mass murderers in history are atheist. Even if they were, they didn’t kill in the name of atheism. Even if they did, atheists don’t make claims of superior morality because of atheism (whereas religion does). Even if they did, that is irrelevant to whether or not atheism is true.