Rubbish. Atheism has probably caused more deaths in wars than religion:
Religion is the cause of a very small minority of wars. Phillips and Axelrod’s three-volume Encyclopedia of Wars lays out the simple facts. In 5 millennia worth of wars - 1,763 total - only 123 (or about 7%) were religious in nature. Furthermore, if you remove the 66 wars waged in the name of Islam, that number is cut down to a little more than 3%. A second scholarly source, The Encyclopedia of War edited by Gordon Martel, confirms this data, concluding that only 6% of the wars listed in its pages can be labeled religious wars. Finally, a 2014 report from the Institute for Economics and Peace further debunks this myth.
We didn’t stop there. We showed students it actually gets worse for the atheists’ claim. A strong case can be made that atheism, not religion, and certainly not Christianity, is responsible for a far greater degree of bloodshed. Indeed, R.J. Rummel’s work in his books, Lethal Politics and Death by Government has the secular body count at more than 100 million in the 20th century alone. Millions have died at the hands of atheist regimes like Mao Zedong, Joseph Stalin, Adolph Hitler, Vladmir Lenin, and others.
Debunking the Religious Wars Myth
“Religion is the cause of most wars,” declared our atheist guest. A few students shot nervous glances at me, hoping I would jump in.