I have been reading Tenra Bansho Zero, and it’s really interesting to see how religion is handled in the default setting. Unlike most non-historical western RPGs, each of the religious groups has a very specific real world antecedent that should be immediately recognizable by those that are familiar with Buddhist history.
Phoenix Sect. Tiantai/Cheontae/Tendai Buddhism; most institutionalized. The Phoenix Sect is accepted as “official” Buddhism by the Shinto techno-priest overlords of Tenra. Mt. Hiei is obviously the inspiration for Suzaku Mountain.
Ebon Mountain. Chan/Son/Zen Buddhism, concerned more with individual enlightenment, also most associated with martial arts.
Bright Lotus. Pure Land Buddhism; salvation through recitation of a mantra. Popular with common people due to the accessibility of the teachings.
(These are oversimplifications, but they are not mischaracterizations.)
How many western RPGs create fantasy versions of Christian sects? Not many. The reason is probably rooted in the satanic panic, but it is nonetheless odd that the west is more sensitive about tapping directly into religious heritage for fantasy inspiration, preferring to go the safer route by appropriating things that are at least one level removed from direct religious practice.
There are some stirrings of deviations from this tendency (for example, the 30 Years War setting for LotFP’s Better Than Any Man, and this post about Biblical mythology from Beedo, though it is worth noting that both of these are more directly historical than Tenra). The Books of Pandemonium, by Rafael Chandler, about a war between heaven and hell on earth, might fit the brief, though I haven’t read it myself, so I don’t know how directly it draws from Christian doctrine.