Even if you think that it’s a completely man-made concept, you have to admit that as much as we take it for granted now, a God (not “god”) that is the only one, that controls everything, and most importantly, is everywhere, was something very new and very different compared to what existed in the world at that time.
The Israelites had a very different view of theology than what everyone else was doing at the time. Even acknowledging that another god existed was wrong to them. Up until then, you got conquered, you took someone else’s gods and meshed them with your existing ones, or added a few new slots at the temple, but this was a religion that didn’t leave room for compromises. I’d like to think that that’s because truth doesn’t leave room to compromise for lies, but a lot of people will disagree.
Now the dominant religions in the world (Christianity, Islam, and because of modern Israel’s importance to geopolitics, Judaism) are all exclusive, universal, and monotheistic, and that’s more or less crystalized religious interaction for the world, but wars existed before any of them existed and they would exist without them. But hopefully, for all of the strife that’s been caused in their names, one of them is right.