That's actually pretty true. I see religion as the explanation for everything we can't understand. Primitive humans understood almost nothing, so everything was some God doing something. We had gods of air and water and stones and harvest…

The more we know, the more God is refined down. Now there's this sense that for every problem, science may figure out a solution. So in a real sense, you're exactly right:
Then – "who makes the crops grow? God does."
Now – "what makes the crops grow? Things like sun, rain, and nutrients in the soil."

So God has been whittled down to only the things that can literally never be proven or disproven and nothing more. That must be frustrating.