As a response, I'd like to say that it is much more likely that money, or the lack thereof, has started more wars than any other reason.

Religion, not specifically Christianity, has been behind quite a few as well, but I'd be willing to bet that, somewhere deep down, some religious leader got greedy, and then used the faith of the followers to get them to rise up and, in the name of "their" God (or whoever), smite the unbelievers, and coincedentally, take away all this filthy money that they won't be needing now that they're in Hell (or wherever).