The Flying Spaghetti Monster (FSM) is the deity of the Church of the Flying Spaghetti Monster or Pastafarianism. Created in 2005 by Oregon State physics graduate Bobby Henderson, it was originally intended as a satirical protest against the decision by the Kansas State Board of Education to require the teaching of intelligent design as an alternative to evolution in public schools.
In an open letter sent to the Kansas State Board of Education, Henderson parodied the concept of intelligent design by professing belief in a supernatural creator which closely resembles spaghetti and meatballs. Henderson further called for his Pastafarian theory of creation to be allotted equal time in science classrooms alongside intelligent design and evolution. He explained that since the intelligent design movement uses ambiguous references to an unspecified "Intelligent Designer", any conceivable entity may fulfill that role, even a Flying Spaghetti Monster. After Henderson published the letter on his website, it rapidly became an internet phenomenon and a symbol for the case against intelligent design in public schools.
Pastafarian beliefs are presented both on Henderson's website, where he is described as a prophet, and in The Gospel of the Flying Spaghetti Monster. The central belief is that an invisible and undetectable Flying Spaghetti Monster created the universe. Pirates are revered as the original Pastafarians, and Pastafarians assert that a steady decline in the number of pirates has resulted in a significant rise in global temperature. Pastafarians celebrate every Friday as a holy day. This is the holiest of Pastafarian holidays, which include Ramendan, Pastover, and Holiday. Pastafarians have also vastly popularized International Talk Like A Pirate Day. Oh, and they believe Heaven has a beer volcano and a stripper factory. Hell has those things, too, but the beer is stale, the strippers have sexually transmitted diseases, and you are punished with wings on your back that make it impossible for you to lie down comfortably.
It should be noted that, while Pastafarianism originated as satire, it has also been treated as a legitimate religion with only one absolutely core tenet, which is the rejection of dogma.note As such, being Pastafarian does not require that one actually believes in the existence of the FSM or any of the purported historical details; indeed, it's entirely possible to be both Pastafarian and almost any other 'standard' religion — it is not synonymous with atheism.note
For its origins, see the manga Franken Fran. Yes, this means the FSM has made it to Japan.
Has little to do with Creepypasta.