There's different "flavors" of Satanism, check out The Satanic Temple as well. They do more things relevant to secularism and work with the FFRF among others.

You're right. But I like the concept, the re-imagining, essentially changing the story that I don't like so it's acceptable to me. I don't think Frodo is real either but I can still like LOTR.

In it's original form (ie an everyday word in a language) Satan just means the opposer. There wasn't a "devil" of any sorts, sky daddy even sent his own angels as a Satan in various passages. Also Satanism bases Satan/Lúcifer from the character created by Romantic era poets such as Shelley, Blake, Byron and France. It is just a literary figure that identifies a philosophy of fighting tyranny and promoting freedom of will and thought.