@Jeff, If I'm about to get killed, I wouldn't really care if the person killing me is fighting for his religion or for his political leader or for resources. I'd just be sad I was getting killed.
People are willing to fight and die for ideologies. Religions are ideologies. But if you remove religion there will different ideologies people will die for. (See the USSR, French revolution, etc.)
And even that doesn't describe a huge amount of wars.
Do you think Bush and Obama were droning and warring with the Middle-East because of religion? No, they were doing it for resources and power. Actually, I suspect a huge amount of wars in the past were economical in nature and not due to religion. Like, the civil war, revolutionary war, war of 1812, were all motivated much more due to economical reasons than religion.
I think it's quite naive to think that religion is the reason behind most of the wars. If you had to point to one thing that was the biggest culprit, it would be resources.