Religion, more than likely, started out with primative man being terrified by thunderstorms, earthquakes, and volcaic eruptions. He sought to appease these angry things lest he be destroyed by them. As mankind evolved, he became more aware of morality and spirituality. His more evolved conscience constantly reminding him of his 'missing the mark' and others 'missing the mark' may have led him to appeal to his creator or creators for mercy by offering sacrifices, lest violent thunderstoms, earthquakes, and volcanic eruptions be unleashed upon him for having not lived up to the moral expectations of whatever placed this innate awareness in him. As primative man wandered, he may have developed different ways to appease these 'gods' and thus different religions came into existence. This does not negate God's existence. It just shows how God allowed mankind to sort of 'grow up' so to speak. After mankind evolved to the point where he could be communicated to, God did start to communicate with him