Demons and Unclean Spirits

Many Jews, Christians, and other ancient Mediterranean peoples held that their world was populated with invisible, intermediary spirits. This often included evil demons, offspring of fallen angels who harried humans with bodily possession, illness, temptation, and other afflictions.

What does the Bible say about demons?

The Hebrew Bible has relatively little to say about “demons” proper. The term, which originates in ancient Greek (daimon), does not have a direct equivalent in Hebrew. The Septuagint, the most prominent Greek translation of the Hebrew Bible, uses “demon” primarily to refer to foreign (non-Israelite) gods, rather than evil spirits per se. Nevertheless, there are passages where demon-like creatures may be implied (see Isa 34:14–15) or where foreign gods may carry demonic valences (see Deut 32:17).

The New Testament, however, includes several narratives that unambiguously feature demons, and especially demonic possession. Jesus’s first miracle in the Gospel of Mark, for example, is an exorcism in a Capernaum synagogue (Mark 1:21–28). Jesus also performs exorcisms in the Gospels of Matthew and Luke. The Gospel of John does not include any exorcisms, though it does report an accusation that Jesus was possessed by a demon (8:48). We encounter demons in other New Testament texts, such as First Corinthians, where demons are associated with non-Jewish sacrificial meat (1 Cor 8, 10), as well as the book of Revelation, where demons help arrange the battle of Armageddon (16:14–16).

The demons of the New Testament are firmly rooted in ancient Jewish demonologies, especially those of Second Temple Judaism. The idea that demons could possess bodies and yet also be cast out by ritual experts, for example, is found in ancient Jewish texts such as the Dead Sea Scrolls and the writings of Josephus.

Where do demons come from?

According to the most common account among ancient Jews and Christians, demons were the postmortem spirits of long-deceased primordial giants, who had come about thanks to the illicit union between fallen angels and mortal women.

This narrative is found in the Book of the Watchers, a Second Temple Jewish text that was later collected as part of 1 Enoch. It reports that angels, appointed to watch over the earth (hence, “the Watchers”), descended to earth and mated with mortal women. This resulted in the birth of gigantic creatures who wreaked havoc on the earth. When God sent the worldwide flood (sparing only Noah and his family), these giants drowned, but their spirits lived on as “evil spirits” or “demons.” References to demons as “unclean spirits” possibly originate in this narrative: the giants (and thus also their spirits) were unclean because they were the result of a forbidden union between heavenly and earthly creatures.

While other explanations for the origins of demons were available to ancient Jews and Christians—see the Treatise of the Two Spirits or the Testament of Solomon for alternative perspectives—the Book of Watchers was broadly popular among ancient Jews and Christians and formed a common explanation for the origins of demons.

What functions did demons serve?

Demons were thought to be the causes of various individual and social ills, such as disease, natural disasters, false religion, and illicit knowledge. As noted already, demons also sometimes took possession of the human body, an aptitude that likely stemmed from their origins within fleshly (giant) bodies. To thwart these ills, ancient Jews and Christians formulated many ritual practices, including exorcism, liturgical prayer, and ritualistic movements such as the signing of the cross. Demons were also invoked as part of magical spells and incantations.

For many ancient Jews and Christians, demons were part of an apocalyptic evil front under the leadership of a chief demon (Satan, for example). The demons will eventually face a day of judgment, however, when their powers will be stripped away. Jesus’s exorcisms in the gospels were likely interpreted as signs that God’s final defeat of evil had been inaugurated.

Many ancient intellectuals turned to demons to help formulate important parts of their theological or philosophical systems. Early Christian theologians, for example, often explained Christian heresy as stemming from demonic influence. Sara Ronis has noted, moreover, that rabbinic writers cited demons in their deliberations regarding Jewish law and ethics.

What about Socrates’s demon?

Outside of the New Testament, the most famous appearance of the demonic in ancient literature occurs in Plato’s Apology, where Socrates reveals that he had been guided by an inner demon. It was common in the ancient Greco-Roman world to use the term demon to refer to divine or semi-divine forces, whether good, evil, or ambivalent.

Socrates uses the term to refer to a benevolent divine force that helped shape his philosophy. This departs from the standard usage of most Jews and Christians, who more commonly held that demons were wholly evil. Nevertheless, ancient Greco-Romans shared many ideas in common with Jews and Christians regarding demons, including their possible involvement in magic, their being made out of airy bodies, and their potential influence on human decisions and fate.  

Thus, ancient Jewish and Christian demonologies, including those found in the Bible, must be understood as fully at home within the broader cultural context of the Greco-Roman Mediterranean. Demons helped ancient Jews, Christians, and others make sense of their world, whether it be the threat of death, the pains of life, or the mystifying forces that sometimes shape human experience.