A parody religion or mock religion is either a parody of a religion, sect or cult, or a relatively unserious religion that many people may take as being too esoteric to be classified as a "real" religion. A parody religion can be a parody of several religions, sects, gurus and cults at the same time. Or, it can be a parody of no particular religion, instead parodying the concept of religious belief. In some parody religions the emphasis is on making fun and being a convenient excuse for pleasant social interaction among like-minded, e.g. the Church of the SubGenius. Other parody religions target a specific religion, sect, cult, or new religious movement.
With some parody religions, only ex-members of the specific group being parodied may understand it or be interested in it. Other parody religions are aimed at highlighting deficiencies in particular pro-religious arguments — the thinking being that if a given argument can also be used to support a clear parody, then the original argument is clearly flawed (an example of this is the Flying Spaghetti Monster, which parodies the equal time argument employed by intelligent design Creationism).
Several religions that are classified as parody religions have a number of relatively serious followers who embrace the perceived absurdity of these religions as spiritually significant, a decidedly post-modern approach to religion. For instance, in Discordianism it may be hard to tell if even these "serious" followers are not just taking part in an even bigger joke. This joke, in turn, may be part of a greater path to enlightenment, and so on ad infinitum.
See also the Wikia project: