To me, religion is man-made, not god-made. It serves a purpose similar (if not identical) to that of philosophy and science, two other man-made concepts.
There is nothing “natural” to religion, philosophy or science. If the Christian God were natural then every person and culture would have naturally gravitated toward Christianity. That God is not known to people unless they are told about his existence is proof that God is a construct. If philosophy and being a philosopher is natural then it would have been of the same structure across all cultures. Again, the fact that Confucius is considered a philosopher is wholly a Western construct. The word and concept “philosophy” is Western, and completely foreign to Eastern thinking. Yet again, if science was natural it would have been the same across all cultures at all times. The fact we needed to discover and develop it means it is constructed.
The only thing not “man-made” is matter. We are part of the material world. We come from the material. So are we not part of nature? In other words, we are nature-made. And it is nature, ironically, which had made us to believe in things that are man-made and the god-made.