And just to be clear, we're contrasting this time of unprecedented peace with entities that have killed in spasms of violence with no apparent public casus belli than "my book is better than your book and it told me to do so?"
Spasms that, in one set of instances, led to the deaths of a significant fraction of the global population?
“Estimates of the number of people killed in the Crusades begin at 1 million (Wertham…) and go as high as 9 million (Robertson…) passing through 3 million (Garrison…) and 5 million (Elson…) along the way. I took the low middle (Garrison’s estimate) as my estimate. The geometric means of the extremes is 3 million.” Matthew White, The Great Big Book of Horrible Things: The Definitive Chronicle of History’s 100 Worst Atrocities (2012), p. 576 (see f.n. 1 under The Crusades).
Or, the religiously affirmed divine right fascists felt during WW2 to rule others as decreed by their holy men? NAZI 'DIVINE RIGHT' TO RULE ASSERTED; Dr. Ley Says Reich's 'Mission' to Dominate Other Nations Is Among War Aims WOULD WIPE OUT BRITAIN 'Annihilation' of Obstacle to German Destiny Demanded by Labor Front Head
https://www.nytimes.com/1939/12/19/archives/nazi-divine-righ...Or, doctrines like "Manifest Destiny" that were religious in origin and preached in church?
http://nationalhumanitiescenter.org/tserve/nineteen/nkeyinfo...
The only way to end the cycle of violence is by embracing the scientific method, rationality, and empathy. Anything else is a step to madness. Voltaire said it best,
There have been people who once said, you believe incomprehensible, contradictory, impossible things, because we have ordered you to do so; therefore do unjust things because we order you to do so. These people reasoned wonderfully. Certainly, whoever has the right to make you absurd has the right to make you unjust.
Or, more succinctly, as Desmond MacCarthy put it via a fictional Voltaire, Ah, my child, as long as people continue to believe absurdities they will continue to commit atrocities!
We must fight irrational lunacy and ensure that the light of enlightenment doesn't die out.