The Jargon File (version 4.4.7, 29 Dec 2003):

Discordianism
 /dis?kor'di?@n?ism/, n.

    The veneration of Eris, a.k.a. Discordia; widely popular among hackers.
    Discordianism was popularized by Robert Shea and Robert Anton Wilson's
    novel Illuminatus! as a sort of self-subverting Dada-Zen for Westerners ?
    it should on no account be taken seriously but is far more serious than
    most jokes. Consider, for example, the Fifth Commandment of the Pentabarf,
    from Principia Discordia: ?A Discordian is Prohibited of Believing What he
    Reads.? Discordianism is usually connected with an elaborate conspiracy
    theory/joke involving millennia-long warfare between the anarcho-surrealist
    partisans of Eris and a malevolent, authoritarian secret society called the
    Illuminati. See Religion in Appendix B, Church of the SubGenius, and ha
    ha only serious.


The Free On-line Dictionary of Computing (30 December 2018):

Discordianism

    /dis-kor'di-*n-ism/ The veneration of Eris,
   also known as Discordia; widely popular among hackers.
   Discordianism was popularised by Robert Shea and Robert Anton
   Wilson's novel "Illuminatus!" as a sort of self-subverting
   Dada-Zen for Westerners - it should on no account be taken
   seriously but is far more serious than most jokes.  Consider,
   for example, the Fifth Commandment of the Pentabarf, from
   "Principia Discordia": "A Discordian is Prohibited of
   Believing What he Reads."  Discordianism is usually connected
   with an elaborate conspiracy theory/joke involving
   millennia-long warfare between the anarcho-surrealist
   partisans of Eris and a malevolent, authoritarian secret
   society called the Illuminati.

   See Religion, Church of the SubGenius, and ha ha only
   serious.

   [Jargon File]

   (1997-04-12)