This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Among the six playable factions in the original 1982 edition of Illuminati sits an entry that is not an invention at all: the Discordian Society, named directly after Discordianism, the real belief system founded in 1963 around a short, strange sacred text called the Principia Discordia. The game's designer, Steve Jackson, was not improvising a joke religion. He was borrowing one already built on jokes that had stopped being only jokes, and the connection to the game runs through a specific person rather than a general cultural mood.
Robert Anton Wilson did not write the Principia Discordia. Its authors were Greg Hill and Kerry Thornley, working under the pen names Malaclypse the Younger and Lord Omar Khayyam Ravenhurst. But Wilson was their friend, was recognized within the movement itself with the mock titles Episkopos, Pope and saint, and wrote the introduction to a 1979 printed edition of the Principia. His larger contribution was co-writing The Illuminatus! Trilogy with Robert Shea in 1975, the very novel that gave Jackson the premise for his game a few years later, threading real Discordian ideas and in-jokes through a work of popular fiction wide enough in reach to hand a card game designer a faction worth naming honestly rather than disguising.
That is the difference worth stating plainly: the Discordian Society faction is not a game inventing a religion to mock. It is a game naming a real one, by way of a novel written partly by one of that religion's own recognized figures.