The One Reality all religions share is that there is a God --- Supreme Being.  Beyond that one commonly shared view --- it's downhill into absurdities.
 
The main absurdity, about which most people are familiar, is the clerical manipulation that "ours is the only religion."  As this is an earth --- plane dimension that for the most part attracts souls with limited spiritual awareness, promoting this concept is easy for souls looking and needing spiritual assurance and desperate for hope.  Under this banner "ours is the only religion," prejudices have been formed, wars have been fought --- all not to perpetuate the Will of God, but rather for the power of clerical manipulators.

The Reality is that there are many different levels of spiritual awareness by souls who have, throughout history, incarnated onto this planet.  As such, the Superconsciouness that a person would attribute to God would of course know that souls would need something they can relate to at a level that they can respond to.  This is why God has allowed so many different religions to exist and even so many factions within different religions.