Small Gods (allthetropes.org)
The 13th Discworld novel and a standalone, although it uses some characters and locations from Pyramids and its events influence later works.- Small Gods (Wikipedia)
Small Gods is the thirteenth of Terry Pratchett’s Discworld novels, published in 1992. It tells the origin of the god Om, and his relations with his prophet, the reformer Brutha. In the process, it satirises religious institutions, people, and practices, and the role of religion in political life.