I had a two day debate with a fellow who said that and more. He also gave a random list of rulers who had caused wars to be fought and because some were Christian, that to him meant that religion caused the particular wars they pursued. It was quite a list including figures such as Napoleon - I guess for this person Napoleon's conquests were in the name of Christianity.
Well this may seem extreme, but there are a lot of people out there who repeat this meme as though it were true in some existential sense. I am thinking about this phenomenon, now so common in the western world. I am not quite sure what to make of it yet and this blog post is a first written effort to sort this out in my mind.
I've considered and studied religion in history for a long time now. I began when quite young, but only as an adult in graduate school did I apply the discipline of academic historical thinking to religion and its place in society. I guess that would be my starting point: that religion, as far as I know, is usually integrated into society. To go to an even more basic level, humans are social animals whose survival has always been predicated on forming societies. That is, we humans are too physically weak to survive and then thrive on the basis of our physical presence. We need to band together, that is, to form a society.
Now, religion.... my present thinking is that human beings seem to always have had a spiritual side - that wondering about the possibility of more than what our senses can apprehend or comprehend is intrinsic to human psychology. This 'feeling' or 'curiosity' or 'need' (and there are probably more to add to this list), I am tentatively assigning the word 'spiritual' and 'spirituality'. I don't know how strong the glue is on the reverse of this label, whether it will peel off at some point, or someone else will scribble out the words and write in their own. But that is where my thinking resides at this moment. Next, I would call 'religion' a society of spiritual individuals. That is, just as humans had to bond together in social groups to survive physically, so too we bonded together in spiritual social groups we call religions. Human beings do not live compartmentalized lives, or we didn't for most of human history. So it is an artifice to say that 'religion' is separate from 'politics' or 'medicine' or 'sex' or any human social activity or grouping. Each individual human contains all these and that means that religion, like all other social groupings is integral to society as a whole.
So in an odd and truncated sense, my debate partner was correct. Wars are fought by people who are religious because they are spiritual, but also the same warriors exist in a political context and a health context and a sexual context .. in short, in a variety of contexts that make up the whole. All these elements of a context go to war, but I doubt that the 'religion context' is primary. The evidence of actual wars shows only a few where religion was the prime motive. For most, power and politics was the initial motivation and the goal.
Politically avaricious rulers discovered in the 16th century that religion could be used to motivate an entire population to fight a war where once wars were the glory and joy and goal of only a warrior class. By using religion, a king or a Duke or a Margrave (titles for monarchs were various) could mobilize an entire population rather than just warriors who lived to fight, or even just a newly invented professional army. This meant that 'civilian' populations also became the deliberate target of armies, rather than accidental victims of soldiers trampling down crops or stealing cows on their way to battle other warriors.
So religion as defined above is involved, but as a tool and as a part of the character of a society but not as a prime motivation.