Thanks everyone who contributed to this very interesting conversation. While reading it, Jung's "Answer to Job" came to mind & the concept of God evolving. I also thought of the Zoroastrian teaching, which as far as I understand it, sees "darkness", "evil" etc - as intrinsic to the process of the material multiverse emerging into reality.
I find the Judaic conception of "evil" to be much more mature and pragmatic than the deeply dualistic Christian doctrine about God and Satan being locked in a battle for souls. The great Gnostic researcher, Elaine Pagels, has written a book on the emergence of Satan, which would be worth looking at for those who are interested.
Regarding the original topic about a specific religion of the Devil, the thing I am drawn to most about the Star of Azazel community & teachings is that it seeks to articulate and illuminate a path towards union between Light & Dark, from within - "as within, so without".
As others have commented, there is much within mainstream Satanism that seems rather juvenile - a reactionary brand of anti-Christianity, rather than a mature path of self-development in it's own right. For some, that might be an important first step, but reacting and rebelling can only take one up to a point on the Path.
For me, the Star of Azazel stands quite differentiated from the vast majority of what I have read & heard about Satanism. I am very glad to have found such a respectful & intelligent community, as well as provocative and insightful texts such as Fosforos. As the saying goes, "Fools rush in where angels fear to tread". Based on my experiences so far, I believe the SoA offers invaluable & wise support for those travelling the Path of Night.