I have no problem in considering Satan to be much, much older than the Abrahamic tradition. At the moment my gut instinct is that the Abrahamic God is *a* god among several. Just as Satan has been known as many different names since creation by different cultures.
I listed my religion as a new Theistic Satanist. I have not yet taken a ritual of initiation or a ritual of blasphemy or anything like that, as suggested on Diane Vera's site. I have been reciting at least one invocation to Satan each night along with a prayer for about a week now. This faith feels right to me, at least the version I have chosen - Theistic Satanism seems to be quite personal and decentralized. I'd like to find out if there is a TS community in the central Texas area, to find like-minded people to talk to in person.
Good luck finding any sort of organized Theistic Satanists in Jesus land. There are a few sides to this coin:
1) Reverse Christians. They believe in the bible, but like Satan more. Just picking a different team basically.
2) Theistic, but not borrowing from Abraham-based faiths. Probably the widest segment of variation. Conventionally not much different from mainstream dogmatic religion with a different idea of what makes a suitable god. Various Demonolators, Temple of Set (at least if you consider Set equivalent to Satan in some fashion), Joy of Satan, etc. Monotheistic, polytheistic, or pantheistic just depending on take.
3) Rational Theists. (My camp... The one that doesn't get much airplay.) Basically and anti-faith that arrives at an understanding of Satan based on some sort of subjective evidence. I am theistic only in the sense that others wouldn't be able to share my perceptions so therefore to them I "just believe" there is a Satan when in fact I believe nothing really at all other than what I experience in life. Much like how Buddhism is a lifestyle so it is with this -- you have to do your own work and there is no taking anyone's word for it. Personally, I am the only one I know.
Generally you wind up here after being an atheist-type (LaVey) Satanist for awhile get into some really odd metaphysical exploration and then realize intensely skeptical worldviews cannot possibly be accurate; or have experiences that such an atheist can't explain - communication with spirits, seeing ghosts, experiencing psychic phenomena, and the like. Since I had direct awareness of such things basically The Church of Satan was a wash for me. It wouldn't matter what they had to say about it.