The history of Baphomet is so absurd and stupid.
In all likelihood it's a corruption of "Muhammad" during one of the Crusades, which would mean it stems from some idiot Islamophobe. In any case, it's a fake name for a fake god that the Knights Templar were accused of worshipping, after they were forced to confess after being tortured.
Then some crackpot occultist, Éliphas Lévi, centuries later, makes up some fake history behind him, invents what he looks like, and gives him attributes he didn't have before.
Then Satanists and right-wing Christians decide that he's a demon of some kind, adding even more fake attributes to an already fake god, which have nothing to do with Lévi's version, just because he looks vaguely like Satan.
That said, I think he looks cool, and there's no real reason to not use him in supernatural horror fiction. I know I intend to. But there's no reason to think he's even remotely real.