In the beginning any religion worked out, if you predicted anything right you were worshiped. Then we began to record things, keep track of predictions. The religions that got more things right won out, survival of the fittest. Religions merged, mutated, created new offshoots.
Over time we learned more science, now the religion that predicted that not paying the sarcrifice to the god to make the sun rise ended up with no followers, gradually religions predicted less and less, signs that god existed were explained away as natural phenonemn.
Today the only religions that haven't been abandoned are ones that predict nothing, have no proof that god exists, in fact make a point that no proof is needed. The only god left is the one that isn't falsifiable