I would say that according to some definitions, "religion" has pretty much disappeared (effectively) for more than half the world today.  Europeans take their religion lightly and most ignore the traditions, and more and more Americans (both North and South) are coming to be similar.

In much of the rest of the world the religion listed in the reference books is not really a religion, for one reason or another.  For example in much of Africa, including the Muslim and Christian parts, it is more magic than religion -- ways to get God to do what you want.  This happens in animism and Hinduism and many flavors of Buddhism and other Chinese religions, where you don't have "God," but "Heaven."  I dunno -- is it okay to call belief in spirits inhabiting a local forest glen and giving these spirits a greeting when you come into it a real "religion?"

We have instincts that lead to expression via religion, such as our submission/dominance instincts, our altruistic instincts, our ability to love and to experience awe and of course our instinct to try to survive, leading to beliefs trying to avoid the reality of death, but none of these can be said to be explicitly a religion instinct.  They are just instincts that sometimes find religious ways to come out.