“Oklahoma doesn’t get to decide what is or is not a religion, especially since Satanism is fairly well established, like it or not.”
Yes, as a matter of fact, they do. I mean, if you can, they can, and that’s certainly what you are doing with that statement.
The fact that it is “fairly well established” does not bear on its validity.
Last time I checked, the government (federal and state) was prohibited from making legal determinations with regard to the practice of religion. That would tend to include whether something is or is not a religion. You and I are free to opine one way or the other all day long; that’s because our opinions do not carry the weight of law.