I would disagree. Atheist are every bit as guilty of mass murder as many religious groups. My argument above had more to do with the attitude many atheist hold presently...take for example Bill Maher, that's the type of attitude I'm referring to. Although I will give him credit for having this attitude about all religious groups rather than just one or two or just christianity and judiasm. His hate and arrogance is evenly spread, which is rare.
But on the topic of mass murder and things like that, it's a bit difficult to compare, let's just say christianity and atheism, let's just focus on two to keep it simple. The difficulty lies in christians who are guilty of this perform these acts in the name of something, therefore it's easy to define and label. Atheist obviously do not do this since there's nothing they would kill in the name of. Now consider atheistic communism, one of the most brutal categories that's ever existed.
"It is true that it's possible that religion can produce evil, and generally when we look closer at the detail it produces evil because the individual people are actually living in a rejection of the tenets of Christianity and a rejection of the God that they are supposed to be following. So it can produce it, but the historical fact is that outright rejection of God and institutionalizing of atheism actually does produce evil on incredible levels. We're talking about tens of millions of people as a result of the rejection of God.[1]" -Gregory Koukl
"Apparently it was just an amazing coincidence that every Communist of historical note publicly declared his atheism … .there have been twenty-eight countries in world history that can be confirmed to have been ruled by regimes with avowed atheists at the helm … These twenty-eight historical regimes have been ruled by eighty-nine atheists, of whom more than half have engaged in democidal162 acts of the sort committed by Stalin and Mao …
The total body count for the ninety years between 1917 and 2007 is approximately 148 million dead at the bloody hands of fifty-two atheists, three times more than all the human beings killed by war, civil war, and individual crime in the entire twentieth century combined." - Vox Day
Full article:
Atheism and Mass Murder - Conservapedia
None of this excuses christian behavior that's similar, although I personally cannot think of examples in christianity that are anywhere equivalent and based on the topic at hand.