Strange, Hitler was religious, and actually a member of the Catholic Church, even though he was not a practicing member.
Stalin was forcing Communism on a population, I don't consider Communism as atheist, now I'm sure the religious nut jobs out there will think that, but considering they also believe in dead zombie that lives in the sky and created everything, their 'talking points' carry very little weight with actual fact.
Not sure who Poi pot is...unless your referring to Pol Pot of Cambodia, Pol Pot's Khmer Rouge were composed of Buddhists and Pol Pot was a Theravada Buddhist. I think I have pretty good knowledge of this, since my Wife is Cambodian, and here parents fled to the US during the Khmer Rogue....I bet you don't even know what Khmer means with out google.
Now lets look at some religious wars:
Thirty Years War kill an estimated 11,500,000, or 2.1% of the WORLD POPULATION
French Wars of Religion 4,000,000
Nigerian Civil War 3,000,000
Second Sudanese Civil War 2,000,000
Crusades 3,000,000 2.3% of the world population
Lebanese Civil War 250,000
For a total of 236,750,000
Now thats not including ethnic cleansing, genocide, or other wars based on religion, thats just a snippet.
There is no "atheistic philosophy of abortion" , again, made up, and a very desperate move by a very desperate person.