Most major religions share very similar esoteric (inner/hidden) teachings with more in common than people may know. They each then created their own exoteric (exterior) traditional/symbolic representations of those esoteric teachings. Then they began fighting over who's metaphor for the same thing is more right.
I left a comment below with a link you may like to check out.
"We are not human beings having a spiritual experience; we are spiritual beings having a human experience"—Pierre Teilhard de Chardin