I’d say one cause for religious war is selfishness. The motivation isn’t truly because “God wills it” or “Allah wills it”, but personal gain.
Pope Urban II launched the First Crusade to extend his power to Constantinople and beyond with an added bonus of fighting off the Seljuqs from previously Christian territory. The Crusaders were in it for all kinds of reasons. If you paid attention to Urban II’s speech, he referred to the Crusades as a pilgrimage. Anybody who died in battle would be remitted of their sins, for they were doing their duty to God. That probably had something to do with it. Also the plentiful amount of loot they would have amounted.
Now I’m not too familiar with Muslim beliefs and practices, but I’ve also heard that some modern terrorism is fueled by the belief that it is to glorify Allah and they will be rewarded with a harem of 72 virgins. Terrorists try to push this concept to take advantage of other individuals who either truly want to please Him or are more inclined to the prospect of a harem. One small problem with that is that Islam does not reward suicide. These small group of terrorists twist words and blur the line between martyrdom and suicide to take advantage of the rest of the population, especially the uneducated, for the sake of fighting the opposition.
On both sides, there was also a little bit of fear involved. Each side was afraid for their own sakes, their own fates, their own souls. They wanted to go to Heaven or any similar paradise, and they were told that going to war for the sake of their savior would make them shoe-ins for salvation. Any doubts they might have had about whether what they were doing as wrong would either be vindicated by calling the acts of war “on the behalf of God” or overshadowed by their own fear of damnation. Again, personal gain: getting into heaven. It’s a dangerous incentive that I think we’re all guilty of wanting. It’s not bad to want it, but sometimes it distracts us from the true motives for having faith.
Furthermore, I think religious wars are about spreading the influence of one’s own religion to another territory or purging another influence from your own territory. Isn’t that also personal gain? It’s because it’s YOUR religion and YOUR territory. You have invested some of yourself in these properties, so again it’s about you and what is yours. We want OUR religion to be the one that is right. If we just had religion as is, not place our ownership on it, I don’t think there would be too much call for religious wars.
So whether it be selfishness or even slightly enlightened self interest (“for the glory of God. My God”) a lot of these wars are a result of us wanting to make it about ourselves. We’ve got to take ourselves out of the picture. Let the ways of God, or whoever we choose, be done through us, not by us. Don’t confuse that with blind faith. One you have to work for, one you don’t.
Translations of Pope Urban’s Speech: http://www.cbn.com/spirituallife/ChurchAndMinistry/ChurchHistory/Crusades_PopeUrbanClermontSpeech.aspx
Interesting blog post on the Reward of 72 Virgins: http://theuglytruth.wordpress.com/2007/03/04/debunking-the-suicide-for-72-virgins-myth/
