Incorrect. No one has ever been killed in the name of atheism. Hitler was a Christian and Stalin worshipped the state, so in that sense, he wasn't atheist at all because he saw himself as a god. The "arguments" that the religious use to try and put the blame on atheists for the millions of people killed in the 20th century are intellectually dishonest and flat out wrong.
[Religion] in its very essence is the mortal enemy of Communism. —Leon Trotskii, Pravda, June 24, 1923
“Atheism is the natural and inseparable part of Communism.” (attributed to Vladimir I. Lenin)
“Our program necessarily includes the propaganda of atheism.” (V.I. Lenin)
“We do not fight against believers and not even clergymen. WE FIGHT AGAINST GOD to snatch believers from Him.” (Vechernaia Moskva, a Soviet newspaper)
Quite a large number of people have been killed in the name of atheism, to deny so is to ignore countless clergy, believers, and church members that were specifically targeted by the anti-religious policies of the Soviet Union and Communist China, not to mention many other countries that had policies of State Atheism.
I never mentioned Hitler, so bringing him up is irrelevant.
And Stalin did not worship the state nor himself, nor believe he was a God. You may call him fanatical, ruthless, an ideologue, but there is no evidence that he held religious views in the supernatural, nor that he worshipped the state or himself. Unless of course, as I suspect you are doing deliberately, you are obtusely stretching the meaning of words in order to make Stalin religious so he fits nicely within your preconceived notions that anti-theism has never killed anyone. Words DO have meanings however - to be religious is to believe in a ritualised supernatural and divine force, which Stalin did not, and to worship is a religious act towards a supernatural force, usually a deity, which Stalin could not do as he was an atheist.
I am also not religious, so to assume so in your argument once again shows that you are using preconceived notions rather than actual arguments. Atheism is a neutral position to be sure, but anti-theism is not. Millions have been killed under State Atheist policies for refusing to give up worshipping their chosen deity. The Soviet Union alone had policies of systematic extermination of clergymen and noted worshippers and proselytisers of faith.
If you would like to read further on the repercussions of state atheism, I would recommend starting here:
http://en.wikipedia.org/wiki/Religion_in_the_Soviet_Union
The section has many links to the anti-religious campaigns of the Soviet Union, and China likewise has a good wiki page with a lot of good links. I would also recommend historian Steven Merritt Miner's book Stalin's Holy War, if you wish for a heftier read. He goes into the unusual role religion played under Stalin's regime - being persecuted and killed, but also having this relaxed during WW2 to give greater cause for the fight, before being made illegal again afterwards.