God is Clear

In the ancient world, every peoples had their own god, and their god was tied directly to their daily experience. So the god in Egypt was presumed to be a sun god because the sun guided their existence. The gods in other areas similarly reflected the areas in which their peoples lived and the things they depended on. And those things were the only things those gods were responsible for or had control over. Egypt's "sun god" only controlled the sun. Nothing else. 

So when the Arameans encountered Israel in the mountains and were soundly defeated, it only made sense to them to deduce that the Lord must be a god of the mountains. Thus, if they were to change the battlefield and draw the Israelites out of the mountains, their God would become powerless to help them and the Arameans would earn a decisive victory. 

Now, keep in mind that at the time, Israel (which indicates only the northern kingdom, as the two had long ago split) had a wicked king - Ahab. God wasn't particularly impressed with Ahab and was not exactly delighting in what Ahab was doing. God was already planning judgment against Ahab. 

But you do not just make presumptions that the God of the Universe, Lord of all Creation, is a little-g god only of the mountains. 

So God sends word to Ahab through the prophet and says, "Look. The Arameans said I'm only a god of the mountains, so I'm going to let you beat them and beat them badly in the flat lands, just so they get that I Am....God of the Universe."

In other words, God says - let Me be clear. 

And clear, He is. 

It's this kind of clarity that can give us confidence to believe the things we think we know about God. The things that we've been taught or have discovered through His Word. Sometimes, it's hard for us to hold on too tightly to these things because we have lingering questions or they're bigger than we can wrap our brains around or we're not sure they're exactly correct (and these hesitations are not completely unfounded - our understanding is limited by our finite human nature). 

But we need not worry about such things. Because as this story demonstrates, if we've got something wrong about God, He'll correct us. If we've made God too small, He'll correct us. If we have somehow turned God into a little-g god of limited domain, He'll correct us. And He'll be very clear about it. 

Israel didn't gain just a little victory over the Arameans on the flat land; they got a sound defeat and a full surrender. Why? 

Because the Lord our God is not some little-g god of the mountains. And He was out to make that one thing very clear.