Prove it for all known history with numbers and references. People have been mass killing each other for thousands of years for religious/religous based ethnic genocide, wars, conflicts. Economics and politics are distant 2nd or 3rd, splus many supposed politically driven mass murdeer goes back to religion. A prime example is the genocidic deportation and transportation of Armenian Christians in the early 1900s by the Ottoman Turks in Turkey. Believed to have killed over 1.5 million Armenians. This was is recognized as the first organized genocide and predated the Nazi Holocaust by 25++ years---it is also recognized in history as the "first holocaust."
One example. Can Google more if needed. But just reinforces my point: you need to do some serious reading of history!!! A little overview of history in high school does not make you a historian. Here is a web site that offers a long list of religous based death and wars. http://www.theskepticalreview.com/JAHPoliticsDeathToll.html
