A religious war or holy war (Latin: bellum sacrum) is a war primarily caused or justified by differences in religion. In the modern period, debates are common over the extent to which religious, economic, or ethnic aspects of a conflict predominate in a given war. According to the Encyclopedia of Wars, out of all 1,763 known/recorded historical conflicts, 123, or 6.98%, had religion as their primary cause. Matthew White's The Great Big Book of Horrible Things gives religion as the primary cause of 11 of the world's 100 deadliest atrocities. In several conflicts including the Israeli–Palestinian conflict, the Syrian civil war, and the wars in Afghanistan and Iraq, religious elements are overtly present but variously described as fundamentalism or religious extremism—depending upon the observer's sympathies. However, studies on these cases often conclude that ethnic animosities drive much of the conflicts.
