You may not consciously believe in the flying spaghetti monster, but if you affirm Multiverse Theory–as many atheists, agnostics, and anti-theists do–then you really do believe in his Meatball Noodliness. Here’s how.
Premise 1: To account for the vast improbabilities of this universe, this universe is treated as one among many, perhaps, infinite universes [Multiverse theory]
Premise 2: Given infinite (or nearly infinite) universes every logical possibility becomes a metaphysical inevitability (or near inevitability) [i.e., all possible options are tried, so every remotely possible state eventually occurs]
Premise 3: The Flying Spaghetti Monster is logical possible [as are unicorns, leprechauns, tooth fairies, etc.] since they are not logically incoherent.
Conclusion: Therefore, the Flying Spaghetti Monster exists.
There you have it. If one agrees with multiverse theory, where the number of universes are so vastly expanded as to make inevitiabilities out of the many improbabilities of this universe, it is virtually certain that at least one of those many universes has a flying spaghetti monster. For that matter, one may add to the collection of actualized creatures, unicorns, fairy god mothers, tooth fairies, leprechauns, and honest lawyers. All of these exist!!!