The rivalry between the three great, monotheistic religions (Christianity, Judaism and Islam) earns the top spot because it is without a doubt, and by a huge margin, the bloodiest conflict on this list.
Historically, it’s may be difficult to pinpoint an exact time when it all got started. The Islamic religion, marking its beginning with the writing of the Quran in 610 AD, is surely the latecomer of the three. Long before this, however, the Christians and the Jews had been going at it pretty bad, beginning with Jesus Christ’s crucifixion in 33 AD by Roman executioners following a Jewish conviction (this was complicated). This enmity intensified incalculably with the Roman Emperor Constantine I’s conversion to Christianity in 312 AD, an event argued by some authors, such as James P. Cook, to have paved the way for Christian persecution against Jews for the remainder of European history.
But we could go even further back than that. In the year 701 BC, an enormous Assyrian army under the command of Sennacherib attempted to conquer the Israelite city of Jerusalem. Had this attempt succeeded, perhaps the very notion of monotheism, which at the time was unique to the Israelites, would have been lost forever. On the contrary, the Israelite victory further cemented their faith in a single God, so much so that it persevered even when they were conquered and enslaved by the Babylonians shortly after. Further back still, all three religions ultimately trace their legacy to the prophet Abraham, who lived in Ur around 2,000 BC, which is pushing the limits of what we would consider civilization itself.
So anyway, once the Arab Muslims sprung up and conquered Jerusalem in 638, the real commotion began. Going down the timeline, there is no shortage of barbarism between all three groups, including but not limited to the following: No less than ten Crusades to Jerusalem by European Christians; the persecution and purge of Jews, Muslims and even Christians, by Christian inquisitors in Spain; and of course, most tragically and notoriously, the mass extermination of Jews in German occupied lands by, and I use this application hesitantly, Christian Nazis in World War II. The Jewish holocaust of the 20th century, a fact openly denied by some prominent Muslims, no doubt was highly influenced by a previous and less-talked-about conflict, namely, the genocide against Armenian Christians at the hands of the Ottoman Turks (a German ally, notice) during the first world war. All this is in addition to singular acts of violence, such as the 1972 Munich Olympics massacre.
This past year, as one last example of how the fire continues to rage, a self-ordained Christian pastor in Florida zealously proclaimed 9/11 to be “International Burn-A-Koran Day” as a way of commemorating the WTC attacks, which were quoted by Osama Bin Laden as being necessary because of the American support of Israel. Those attacks killed over 3,000 Christian, Jewish and Muslim people.