[@Virgil]: The Iron Rose Knights originated as a firmly Mayonite order. Now, they're not exactly a religious knight order, but they're still attached to their roots.

Among humans, though, worship of Reon and Mayon is extremely widespread and is the largest religion on the continent, dwarfing the next human religion in numbers, so it's very likely any human is likely going to share in that religion. Technically, someone who doesn't wouldn't be blocked, but it would be strange to the other knights and extremely uncommon.