The Pure in Faith were a sub-sect of the Masadan branch of the Church of Humanity Unchained.
Holding a more extreme anti-technology stance than even their fellow Masadans, the Pure in Faith rejected reading and writing, as they considered them to be the first steps in the road to technological corruption. While mainstream Masadans kept only their women illiterate, the Pure in Faith forbid even their men to learn how to read and write.
The Pure in Faith kept themselves in isolated enclaves all over Masada, with little interaction with the rest of Masadan society except by providing their men as soldiers; Pure in Faith soldiers were regarded to be among the most ferocious and unquestioning warriors of the Faithful. (HHA4.1: PL)