Satan, also known as the Devil, is an entity in the Abrahamic religions that seduces humans into sin or falsehood.  In Christianity and Islam, he is usually seen as either a fallen angel or a jinn who used to possess great piety and beauty but rebelled against God.

The Christian figure of Satan is viewed as a horned, red, demonic human figure with a pointy tail and sometimes hooves.  Sinners are sent to the domain of Satan after death—to hell, an underground world of fire and sadistic demons under Satan’s command.

Other versions of Satan appear as a Zoroastrian Devil and Jewish Kabbalism, but the name “Satan” first appeared in the Book of Numbers in the Bible, used as a term describing defiance.  In the Book of Job, Satan is an accusing angel.  In the apocryphal Book of Enoch (written in the first century B.C.) Satan is a member of the Watchers, a group of fallen angels.

In the New Testament, Satan is established as a nemesis of Jesus Christ and the final book of the Bible, Revelations, he is the ultimate evil.

The words “Satanism” and “Satanist” appeared in English and French during the 1500s, when the words were used by Christian groups to attack other, rival Christian groups.  For example, a Roman Catholic tract in 1565 condemned the “heresies, blasphemies, and sathanismes [sic]” of Protestants.  Anyone who didn’t follow one’s own “pure” Christian views was condemned.

Gradually, it morphed into meaning anyone leading an immoral lifestyle.  It wasn’t until the late 1800s that it was applied to those suspected of consciously and deliberately venerating Satan.

According to online sources, during the early modern period, fear of Satanists took the form of witch trials (1400s to 1700s, which doesn’t seem all that modern to me, but hey, witch hysterias, and the inquisition).  Across both Protestant and Catholic regions, witch trials emerged.  Between 30,000 and 50,000 people were executed as Satanic witches.

Skipping lightly past offshoots and variations, prior to the 20th Century, Satanism did not exist as a real, organized religion.  Satanism is a modern, largely non-theistic religion based on literary, artistic, and philosophical interpretations of the central figure of evil.  It wasn’t until April 30, 1966 that the Church of Satan was formalized.

Anton LaVey’s Satanic Bible was published in 1969.  His teachings promoted indulgence, vital existence, undefiled wisdom, kindness to those who deserve it, responsibility to the responsible, and an eye for an eye code of ethics.  In his view, a Satanist is carnal, physical and pragmatic, enjoying a physical existence, propagating a naturalistic worldview that seems human as animals dieting in an amoral universe.  The ideal Satanist should be individualistic and noon-conformist.   He encouraged an individual’s pride, self-respect, and self-realization by satisfying the ego’s desires.  Self-indulgence is a good thing.  He said hate and aggression are necessary and advantageous for survival.  Bottom line: he praised the seven deadly sins as virtues.

By the 1970s, groups were splintering off to form alternative churches.  In 1978, the U.S. Army included the faith in its manual for chaplains, “Religious Requirements and Practices.”

The most successful of the church divisions is The Satanic Temple, opened in Houston in 2015.  The Temple calls itself a non-theistic religion embracing the Devil as a symbolic form of rebellion in the tradition of Milton.  It devotes itself to political action focused on the separation of church and state, religious equality, and reproductive rights.

Note: Practitioners of LeVey’s version of Satanism do not believe that Satan literally exists and do not worship him. For them, Satan is an archetype for adversary, who represents pride, carnality, and enlightenment.  The Devil is a symbol of defiance against the Abrahamic faiths that “suppress humanity’s natural instincts.”

However, Theistic Satanism (Spiritual Satanism or Devi worship) holds the primary belief that Satan is an actual deity to revere and worship.  They believe in magic and ritual, often focusing solely on devotion.

Bottom line for writers: Satanism isn’t a unitary thing.  If Satanism figures into your plot or character characteristics, do your homework, particularly for any historical setting.