The Mellorite Fenestra Church (Sanctuary's Lot Supplement)
From D&D Wiki
The Mellorite Fenestra Church[edit]
The result of a very old division of the Fenestra Orthodox Church, the Mellorites are a very large, well-established faith. Differing from the Orthodoxy in that The Mellorite Fenestra Church worships Sanctuary above all others with Rune and Monolyth as far less significant entities, while the Lords of the Ten towers are venerated as equal to (but separate from) the saints. The Mellorite church has its own list of saints, independent from the Orthodox hallowed catalog.
They are notable for having a long, storied tradition of sheltering and training magicians (almost exclusively Disciples of the Moon) going back more than two thousand years. Historically, Mellorite leadership has proclaimed their magicians to be the backbone of the church. Indeed, some Mellorite Hierarchs have numbered amongst the most powerful magicians who ever lived.
Throughout its history, the Mellorites have frequently been in theological, political, and (rarely) martial conflict with the Fenestra Orthodox Church. More recently, they have also contended with the Illuster Sacellum, which has been greatly antagonistic to any faith it finds heretical.