Belief in Satan worship is often viewed as an embarrassing throwback to the superstitions of another time. And "selling your soul to the Devil"? Nothing more than an overworked theme in literature and opera. To the contrary, Bob and Gretchen Passantino show how, in the midst of prevailing attitudes of skepticism and disbelief, Satanism has made unprecedented inroads into our society.
Satanism by Bob and Gretchen Passantino is part of the Zondervan "Cults" series. This is a quick read at 96 pages and has quite a bit of good background info on Satanism.
The book really excels at explaining the movement's roots, development and general mindset. If you want some solid arguments to use against satanism then there are probably better books for you. While there is a whole section on witnessing to satanists it felt lacking and underdeveloped.
In general I would recommend this as a very intro level book on Satanism and the occult.