http://www.huffingtonpost.com/rabbi-...b_1400766.html
"History simply does not support the hypothesis that religion is the major cause of conflict. The wars of the ancient world were rarely, if ever, based on religion. These wars were for territorial conquest, to control borders, secure trade routes, or respond to an internal challenge to political authority. In fact, the ancient conquerors, whether Egyptian, Babylonian, Persian, Greek, or Roman, openly welcomed the religious beliefs of those they conquered, and often added the new gods to their own pantheon.
Medieval and Renaissance wars were also typically about control and wealth as city-states vied for power, often with the support, but rarely instigation, of the Church. And the Mongol Asian rampage, which is thought to have killed nearly 30 million people, had no religious component whatsoever.
Most modern wars, including the Napoleonic Campaign, the American Revolution, the French Revolution, the American Civil War, World War I, the Russia Revolution, World War II, and the conflicts in Korea and Vietnam, were not religious in nature or cause. While religious groups have been specifically targeted (most notably in World War II), to claim that religion was the cause is to blame the victim and to misunderstand the perpetrators' motives, which were nationalistic and ethnic, not religious.
Similarly, the vast numbers of genocides (those killed in ethic cleanses, purges, etc. that are not connected to a declared war) are not based on religion. It's estimated that over 160 million civilians were killed in genocides in the 20th century alone, with nearly 100 million killed by the Communist states of USSR and China. While some claim that Communism itself is a "state religion" -- because it has an absolute dictator whose word is law and a "holy book" of unchallenged rules -- such a claim simply equates "religion" with the human desire for power, conformance, and control, making any distinctions with other human institutions meaningless."