So the caveman went off and caught a rabbit or a bird and cut its throat so it bled on the rock. It may propitiate the beast that ate my boy, so at least he won't try to do it again. Anyway, I can't just stand around doing nothing, not with that wife of mine yelling at me. And five thousand generations later people are still slitting the throats of lesser creatures at that rock in the conviction, now hallowed by precedence of unknowable antiquity, that it will do some good, and that no matter what happens, it would have been worse if they hadn't gone to the trouble of making this sacrifice. They are doing it because their people have always done it, because it is an act that propitiates their gods and is expected thereby to enhance their individual hopes and prospects, and because it is a way of doing something that they believe will give them some influence over otherwise uncontrollable events.
Religion is an enormously complicated phenomenon.
If its only purpose were an attempt to establish some degree of influence over the unknowable, it probably would have died out by this time, at least in the more modern, educated sectors of global society. Different religions differ widely from each other, but it should be possible to determine whether they share certain structural characteristics. These entities can be immaterial and impersonal, but more often they tend to be anthropomorphic. The true believer accepts the existence of these entities as a matter of faith, not to be questioned. They answer several basic needs, common to all humans.