It was as if Satan was walking the streets of New York...
-- New York Firefighter, regarding 9/11/2001
Evil is, on one level, a cultural construct. The Easter Islanders
believed that stealing, if successful, was virtuous.
This was probably a social mechanism for redistributing scarce
items on a small island.
However some evils--war, genocide, and terrorism to name a few--are
instantly recognizable as such.
The issue of why an omniscient, all-powerful God would
permit such horrors is one of the most difficult (and obvious)
This section of sacred-texts deals with this thorny issue.
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.
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.