Communism and Atheism
If you are an atheist, you hear the old canard about how "atheists" were responsible for all the atrocities of the twentieth century. Neglecting the fact that Hitler was Catholic and never renounced his faith and that the Japanese who participated in the rape of Nanking weren't atheists either. But even if we're talking about explicitly atheistic regimes like those of the Soviet Union and communist China, the fact that those regimes were (are) atheistic doesn't prove that atheism inevitably leads to atrocities nor that atheism is inherently destructive.
Because atheism is nothing more than lack of belief in a god or god(s). Just because Stalin and his minions lacked belief in a god or god(s) isn't proof that that is the reason they committed the atrocities they committed. Just because someone is an atheist doesn't mean that you can attribute everything they think or do to the fact that he or she is an atheist. In order to do that, you'd have to show a causal link of some kind between the person's atheism and those acts. Just saying, "Person A is an atheist and did bad things, therefore Person A did bad things because he or she is an atheist" does not make it so.
To demonstrate why this must be true, let us consider that Stalin was also (to my knowledge) not a collector of stamps. He did not participate in philately, the hobby of stamp-collecting, and as such, could be dubbed an a-philatelist (non-stamp collector). Can we then say that a-philately is the cause of the atrocities Stalin committed, and that only an a-philatelist regime could those atrocities happen? Could we say that a-philatelists are responsible for the atrocities of the 20th century? After all, (as far as a I know), none of the great dictators of the 20th century was a philatelist. Not Hitler, not Pol Pot, not Stalin, not Idi Amin...
But, obviously, the fact that none of these men collected stamps cannot be assumed to be the cause of their disregard for human life without further evidence. The fact is, people do things because of what they do believe, not as much because of what they don't believe. All that being an a-philatelist means is that you don't collect stamps. It says very little about what you do do. In the same way, being an atheist means you lack belief in a god or god(s). It says something about what you don't do (worship a god or god(s) or subscribe to a theist religion) but it says very little about what you do do.
Stalin killed because he wanted power and believed he had a right to it. Hitler killed because he believed the Jews and other undesirables were enemies of the German people and were undermining the rightful ascendance of the Aryan people to world domination. Japanese killed Chinese during the rape of Nanking because they believed themselves superior. They did those things because of what they believed, not because of what they didn't believe.
To posit that atheism was the cause of the tragedies perpetrated by atheistic regimes in the 20th century, we would have to see a marked departure from what we have seen from theistic regimes throughout history. That is to say, if theistic regimes never perpetrated mass killings and atrocities, and atheistic regimes did, then we'd have some evidence that atheism was the cause of those atrocities. However, since atheistic regimes seem to differ little from theistic regimes in terms of bloodthirstiness, especially when we consider the fact that the Nazis were not atheists even though the Soviets were, it's difficult to make the argument that atheism was the cause.
As a poster on a blog I read wrote recently, "Vikings breathed air and raided villages and killed the inhabitants. Therefore governments headed by people who breathe air must all be raiders of villages and murderers."