Keep the Archive Alive!
Note that there aren’t any sacred texts of Satanism per se at this site. Satanism as an organized religion is a very recent phenomena, and books about it are a long way from entering the public domain. Besides, to put a fine point on it, actual Satanists insist that they aren’t evil.
The History of the Devil by Paul Carus 
A comprehensive account of the history of evil, in particular as symbolized by the Christian devil, but also including a wide-ranging survey of other religions. Extensively illustrated.
The Evil Eye by Frederick Thomas Elworthy 
A comprehensive exploration of a somewhat different, and probably more ancient theory of evil, and the ways to ward it off using talismans and gestures. Likewise extensively illustrated.
Devil Worship in France by Arthur Edward Waite 
A.E. Waite debunks false accusations that Freemasons worship the Devil.
The Devils of Loudun by Edmund Goldsmid 
A translation of the primary source on the 1634 mass possession of the nuns of Loudun.