In their study of Satanism, the religious studies scholars Asbjørn Dyrendal, James R. Lewis, and Jesper Aa. Petersen stated that the term Satanism "has a history of being a designation made by people against those whom they dislike; it is a term used for 'othering'". The concept of Satanism is an invention of Christianity, for it relies upon the figure of Satan, a character deriving from Christian mythology.
Elsewhere, Petersen noted that "Satanism as something others do is very different from Satanism as a self-designation".
Eugene Gallagher noted that, as commonly used, Satanism was usually "a polemical, not a descriptive term".
The word "Satan" was not originally a proper name but rather an ordinary noun meaning "the adversary"; in this context it appears at several points in the Old Testament. For instance, in the Book of Samuel, David is presented as the satan ("adversary") of the Philistines, while in the Book of Numbers the term appears as a verb, when God sent an angel to satan ("to oppose") Balaam. Prior to the composition of the New Testament, the idea developed within Jewish communities that Satan was the name of an angel who had rebelled against God and had been cast out of Heaven along with his followers; this account would be incorporated into contemporary texts like the Book of Enoch. This Satan was then featured in parts of the New Testament, where he was presented as a figure who tempted humans to commit sin; in the Book of Matthew and the Book of Luke, he attempted to tempt Jesus of Nazareth as the latter fasted in the wilderness.
The word "Satanism" was adopted into English from the French satanisme. The terms "Satanism" and "Satanist" are first recorded as appearing in the English and French languages during the sixteenth century, when they were used by Christian groups to attack other, rival Christian groups. In a Roman Catholic tract of 1565, the author condemns the "heresies, blasphemies, and sathanismes [sic]" of the Protestants. In an Anglican work of 1559, Anabaptists and other Protestant sects are condemned as "swarmes of Satanistes [sic]". As used in this manner, the term "Satanism" was not used to claim that people literally worshipped Satan, but rather presented the view that through deviating from what the speaker or writer regarded as the true variant of Christianity, they were regarded as being essentially in league with the Devil. During the nineteenth century, the term "Satanism" began to be used to describe those considered to lead a broadly immoral lifestyle, and it was only in the late nineteenth century that it came to be applied in English to individuals who were believed to consciously and deliberately venerate Satan. This latter meaning had appeared earlier in the Swedish language; the Lutheran Bishop Laurentius Paulinus Gothus had described devil-worshipping sorcerers as Sathanister in his
Ethica Christiana, produced between 1615 and 1630.