Quote from Yannis:
Scholars who study religions see several characteristics that are common in the great ones, those who have stood the test of time (this is a very crude summary, but you can do your own research):
a. Belief in God in a personal sense (eg, Christianity, Judaism, Islam, Hinduism, etc) or Godhood (eg, Buddhism, Taoism, Shintoism, etc);
b. Belief that we (humans) are immortal beings and live forever, way past our physical deaths; and belief that the way we behave here in this life affects what happens to us in the long run - to fare well we need to be charitable, kind, truthful, generous, altruistic, etc etc, and these qualities produce in us a sense of deep peace.
c. Belief that these two points above can relate to each other; eg, we can communicate with God or reach for the presence of godhood within us in some way, and thet He tries to communicate with us directly or through the teachings of wise people before us who wrote the various scriptures.