So someone recently posted an answer about the Flying Spaghetti Monster.
Is that acceptable?
I would say that for a religion to be "real" there has to be people who actually claim to believe in it.
I have never seen any credible source of people genuinely claiming to believe in the Flying Spaghetti Monster. It's a parody religion created as a rhetorical device, a joke and as a means to prove a point. Nobody has ever actually believed in it. Therefore, I don't believe it qualifies as an actual religion or mythology in the normal sense.
Sure, there are religions that are created by fraudsters/con-men who don't actually believe what they are promoting, but they usually claim that they do believe it, and they are not trying to be funny. Also, their followers typically do believe it. Thus, they qualify as actual religions.
Similarly so with ancient mythologies. There may be nobody or extremely few who believes in it anymore, but lots of people did believe it in the past.
So since no one anywhere (AFAIK) has ever seriously believed in the Flying Spaghetti Monster, I don't believe it's a proper answer. I might as well have answered The Ellimist (a totally fictional god that no one believes in.)