portrayed as a religious conflict of a Catholic vs. a Protestant faction, while the more fundamental cause of the conflict was supposedly ethnic or nationalistic rather than religious in nature. Since the native Irish were mostly Catholic and the later British-sponsored immigrants were mainly Protestant, the terms become shorthand for the two cultures, but McGarry & O'Leary argued that it would be inaccurate to describe the conflict as a religious one. In their 2015 review of violence and peacemaking in world religions, Irfan Omar and Michael Duffey stated: "This book does not ignore violence committed in the name of religion. Analyses of case studies of seeming religious violence often conclude that ethnic animosities strongly drive violence." Prevalence The definition of 'religious war' and the applicability of religion to war have a strong influence on how many wars may be properly labelled 'religious wars', and thus how prevalent religious wars have been as opposed to other wars. According to Kalevi Holsti (1991, p. 308, Table 12.2), who catalogued and categorised wars from 1648 to 1989 into 24 categories of 'issues that generated wars', 'protect[ion of] religious confrères' (co-religionists) was (one of) the primary cause(s) of 14% of all wars during 1648–1714, 11% during 1715–1814, 10% during 1815–1914, and 0% during 1918–1941 and 1945–1989. Additionally, he found 'ethnic/religious unification/irredenta' to be (one of) the primary cause(s) of 0% of all wars during 1648–1714 and 1715–1814, 6% during 1815–1914, 17% during 1918–1941, and 12% during 1945–1989. In their 1997 Encyclopedia of Wars, authors Charles Phillips and Alan Axelrod documented 1763 notable wars in world history, out of which 121 wars were in the "religious wars" category in the index. They note that before the 17th century, much of the "reasons" for conflicts were explained through the lens of religion and that after that time wars were explained through the lens of wars as a way to further sovereign interests. Some commentators have concluded that only 123 wars (7%) out of these 1763 wars were fundamentally originated by religious motivations. Andrew Holt (2018) traced the origin of the 'only 123 religious wars' claim back to the 2008 book The Irrational Atheist of far-right activist Vox Day, which he notes is slightly adjusted compared to the 121 that is indeed found in the Encyclopedia of Wars itself. The Encyclopedia of War, edited by Gordon Martel, using the criteria that the armed conflict must involve some