Read my book, "A Recipe for Religion," on how to prove the FSM religion is Constitutionally protected as any other religion. However, if you don't want to spend the $.99, research the Seeger Sincere Belief test. There's a lot more (at least legally) to it, but the Seeger test is the seminal case.
As an aside, I find it hilarious when one sectarian argues about the "validity" of their sect's beliefs over another sects. I say we put all religions to a "taste test." The tastiest deity wins. Hmmmm... I know where I'm placing my money!
If there are any other law students, lawyers, or Constitutional scholars who have a love of the First Amendment out there, please feel free to discuss these issues with me.