What about the concept that religion is entirely man-made for the purpose of controling society?

I grew up going to church and believing the teachings, but when I went to a christian college and took a religion cl, my eyes were opened to a concept I had not considered before. There is a concept that in the early stages of society, man developed religion as a way to keep order in society. Without an afterlife, there would be no reason to conform to society or it's morals and life would be chaotic. The differences between the religions is because the principals were developed by people in different regions, so they created their own rules and values. It makes sense if you think about it, which was very troubling for me. I had never before questioned religion.