I did the 4 minute Wikipedia research.

Factors leading to war:

* Historical theories
* Psychological theories
* Anthropological theories
* Sociological theories
* Demographic theories
* Evolutionary psychology theories
* Rationalist theories
* Economic theories
* Marxist theories
* Political science theories

Causes of war:

* Extortionate
* Aggressive
* Colonial
* National liberation
* Religious
* Dynastic
* Trade
* Revolutionary
* Guerrilla

Religious differences are significant, but not one of the major causes of warfare.

Significant exceptions were the massacres of Indian Independence (1947, Hindu vs. Muslim) which I’ve studied. Sheer stupidity. Hundreds of thousands of lives could have been saved if the British handled the withdrawal better. (Are you listening USA?)

Wars, Massacres and Exterminations Due to Religious Intolerance – rateitall.com