Religion is man made institution and not a divine institution. Our primitive forefathers had no religion and knew nothing about God. They started worshiping any source of nature that was either beneficial to them or could cause them incalculable harm.
Thus, they worshiped the Sun, the Moon, the Water, the Rivers, the Mountains, the Oceans, the fire, the snakes, the trees and so on and so forth. Then they made idols symbolising these forces of nature or animal world and started worshiping them. Thereafter, they started worshiping their heroes who performed remarkable feats. When they began to write, they started worshiping those books which were written by wise men and contained words of wisdom or were in praise of the various forces of nature whom they worshiped. Then someone thought that there must be a creator who created all these various sources of energy and they started calling him God and started worshiping Him while still worshiping the various sources of energy as well as their heroes as deities. Then Prophet Mohammad emerged on the scene and abolished the worship of various idols and sources of energy as well as heroes and decreed that only God would be worshiped. Thus came the new religion, Islam but there were other religions also who were also monotheistic. So, no religion is divine but all religions are man made. The latest religion to my knowledge is Arya Samaj of Hindus which was created by Dayanand Saraswati. However, some people questioned the existence of God and sought proof of his existence. Such people were called atheist. Then came certain people like me who were of the view that we could not prove or disprove the existence of God and they were called agnostics. Moreover like other religious people who felt that deliverance from the cycle of births and deaths could be achieved by reciting the name of God or who imagined that one could go to an imaginary place called Heaven which will be full of pleasure and joy, by reciting the name of God, the agnostics felt no need of reciting the name of God. Agnostic also did not believe in the concept of Hell like other religious people who felt that God punished those who did not recite His name or otherwise sinned which actually meant that they acted against the established norms of the society. In a way, religion was also created to see to it that the society formed by the people of that religion was not broken up.