In time long past, there was a sect of Monks called The Brotherhood of Balance. These monks rejected the worship deities. They claimed that "deities" were not of divine power or origin. Instead, they were great heroes and villains whose deeds were exaggerated to the point of worship. The monks did not believe that the worship of gods was an illusion. They spoke that it was a twisted perception.
As time went on, the order became arrogant; treating the worship of gods as common, low-class, a bad habit of the ill-educated. Persons who were not associated with the order or the temple were ignored or not helped. The monks stopped helping others without conditions.
As the order spread, there were many who did not share the monk's views. Namely, those who followed the Chaotic Evil and Lawful Good deities. The most fanatic of these religious orders decided to take it upon themselves to eliminate the Brotherhood by all means necessary.
After several attacks, the survivors fled. Disguised, most found refuge with the Sankarjin. The Brotherhood discovered that their philosophy and the Sankarjin religion has similar beliefs. And as time went on and they moved with the caravan's, the philosophy of the Brotherhood and the way of Atamarue combined.
The revenants of the Brotherhood for reasons unknown began to gather in Khemair. In Khemair, the tales of Ray the Messiah had taken root. Over more time, the Brotherhood adopted Ray as the main hero representative in the place of Atamarue. This helped shape the Philosophy of what we know as Rayism in Tarkazia.
This is also why The Temple of Ray have monks rather than priests or clerics. The Temples of Ray help train people in Exotic Weaponery. The Temple is where one would find the strange and unusual characters that appear in Tarkazia. The Brotherhood helped to bring concepts of "Oriental Arts" into East Tarkazia.
It took five hundred years to develop Rayism. The Temples of Ray have scattered all over Tarkazia.