[cowboyhater]

In the last century more people were executed by atheistic Communism (30 million or so by Stalin, 65 million or so by Mao, millions more by Ho Chi Minh, Pol Pot, Mengistu etc.) and anti-Christian nazism than by all of the wars in all of the other centuries put together since the beginning of history. WWI also was responsible for the death of many millions, and I have never known that to be characterized as a religious war.

Even if your statement were true, it would no more mean that religion caused wars than to say the existence of national boundaries or private property caused wars, since so many wars were simply over land acquisition.