In religion and mythology, occultism and folklore, a demon (or daemon, daimon; from Greek δαίμων daimôn) is a supernatural being that is generally described as a malevolent spirit. However, the original meaning of the word daemon does not carry any negative connotations, which were later projected onto it as Christianity spread.
In Ancient Near Eastern religions as well as in the derived Abrahamic traditions, including ancient and medieval Christian demonology, a demon is considered an "unclean spirit" which may cause demonic possession, to be addressed with an act of exorcism. Western occultism and Renaissance magic, which grew out of an amalgamation of pagan Greco-Roman, Jewish and Christian tradition, a demon is considered a spiritual entity that may be conjured and controlled.
Ancient Greek δαίμων daimōn is a word for "spirit" or "divine power", much like the Latin genius. The Merriam-Webster dictionary gives the etymology of the Greek word as from the verb daiesthai "to divide, distribute." The Greek conception of a δαίμων notably appears in the works of Plato, where it describes the divine inspiration of Socrates. To distinguish the classical Greek concept from its later Christian interpretation, it is usually anglicized as either daemon or daimon rather than demon.
The Greek term does not have any connotations of evil or malevolence. In fact, εὐδαιμονία, literally "good-spiritedness", is a term for "happiness". The term first acquired its now-current evil connotations in the Septuagint translation of the Hebrew Bible, informed by the mythology of the ancient Semitic religions. This connotation was inherited by the Koine text of the New Testament. The medieval and neo-medieval conception of a "demon" in Western civilization (see the Medieval grimoire called the Ars Goetia) derives seamlessly from the ambient popular culture of Late (Roman) Antiquity. Greco-Roman concepts of daemons that passed into Christian culture are discussed in the entry daemon, though it should be duly noted that the term referred only to a spiritual force, not a malevolent supernatural being. The Hellenistic "daemon" eventually came to include many Semitic and Near Eastern gods as evaluated by Christianity.
The supposed existence of demons is an important concept in many modern religions and occultist traditions. In some present-day cultures, demons are still feared in popular superstition, largely due to their alleged power to possess living creatures. In the contemporary Western occultist tradition (perhaps epitomized by the work of Aleister Crowley), a demon, such as Choronzon, the "Demon of the Abyss", is a useful metaphor for certain inner psychological processes, though some may also regard it as an objectively real phenomenon. Some scholars believe that large portions of the demonology (see Asmodai) of Judaism, a key influence on Christianity and Islam, originated in Zoroastrianism, and were transferred to Judaism during the Persian era.
Psychologist Wilhelm Wundt remarks that "among the activities attributed by myths all over the world to demons, the harmful predominate, so that in popular belief bad demons are clearly older than good ones." Sigmund Freud develops on this idea and claims that the concept of demons was derived from the important relation of the living to the dead: "The fact that demons are always regarded as the spirits of those who have died recently shows better than anything the influence of mourning on the origin of the belief in demons."
M. Scott Peck, an American psychiatrist, wrote two books on the subject, People of the Lie: The Hope For Healing Human Evil and Glimpses of the Devil: A Psychiatrist's Personal Accounts of Possession, Exorcism, and Redemption.
Peck describes in some detail several cases involving his patients. In People of the Lie: The Hope For Healing Human Evil he gives some identifying characteristics for evil persons whom he classifies as having a character disorder. In Glimpses of the Devil, A Psychiatrist's Personal Accounts of Possession, Exorcism, and Redemption Peck goes into significant detail describing how he became interested in exorcism in order to debunk the "myth" of possession by evil spirits – only to be convinced otherwise after encountering two cases which did not fit into any category known to psychology or psychiatry. Peck came to the conclusion that possession was a rare phenomenon related to evil. Possessed people are not actually evil; they are doing battle with the forces of evil. His observations on these cases are listed in the Diagnostic and Statistical Manual of Mental Disorders (IV) of the American Psychiatric Association.
Although Peck's earlier work was met with widespread popular acceptance, his work on the topics of evil and possession has generated significant debate and derision. Much was made of his association with (and admiration for) the controversial Malachi Martin, a Roman Catholic priest and a former Jesuit, despite the fact that Peck consistently called Martin a liar and manipulator. Other criticisms leveled against Peck include misdiagnoses based upon a lack of knowledge regarding dissociative identity disorder (formerly known as multiple personality disorder), and a claim that he had transgressed the boundaries of professional ethics by attempting to persuade his patients into accepting Christianity.
In Chaldean mythology the seven evil deities were known as shedu, meaning storm-demons. They were represented in winged bull form, derived from the colossal bulls used as protective genii of royal palaces, the name "shed" assumed also the meaning of a propitious genius in Babylonian magic literature.
It was from Chaldea that the name "shedu" came to the Israelites, and so the writers of the Tanach applied the word as a dylogism to the Canaanite deities in the two passages quoted. But they also spoke of "the destroyer" (Exodus xii. 23) as a demon whose malignant effect upon the houses of the Israelites was to be warded off by the blood of the paschal sacrifice sprinkled upon the lintel and the door-post (a corresponding pagan talisman is mentioned in Isaiah lvii. 8). In II Samuel xxiv; 16 and II Chronicles xxi. 15 the pestilence-dealing demon is called "the destroying angel" (compare "the angel of the Lord" in II Kings xix. 35; Isaiah xxxvii. 36), because, although they are demons, these "evil messengers" (Psalms lxxviii. 49; A. V. "evil angels") do only the bidding of God; they are the agents of His divine wrath.
There are indications that popular Hebrew mythology ascribed to the demons a certain independence, a malevolent character of their own, because they are believed to come forth, not from the heavenly abode of God, but from the nether world .
Hebrew demons were workers of harm. To them were ascribed the various diseases, particularly such as affect the brain and the inner parts. Hence there was a fear of "Shabriri" (lit. "dazzling glare"), the demon of blindness, who rests on uncovered water at night and strikes those with blindness who drink of it; also mentioned were the spirit of catalepsy and the spirit of headache, the demon of epilepsy, and the spirit of nightmare.
These demons were supposed to enter the body and cause the disease while overwhelming or "seizing" the victim (hence "seizure"). To cure such diseases it was necessary to draw out the evil demons by certain incantations and talismanic performances, in which the Essenes excelled. Josephus, who speaks of demons as "spirits of the wicked which enter into men that are alive and kill them", but which can be driven out by a certain root, witnessed such a performance in the presence of the Emperor Vespasian, and ascribed its origin to King Solomon.
Pre-Islamic mythology does not discriminate between gods and demons. The jinn are considered as divinities of inferior rank, having many human attributes: they eat, drink, and procreate their kind, sometimes in conjunction with human beings. The jinn smell and lick things, and have a liking for remnants of food. In eating they use the left hand. Usually they haunt waste and deserted places, especially the thickets where wild beasts gather. Cemeteries and dirty places are also favorite abodes. When appearing to man, jinn sometimes assume the forms of beasts and sometimes those of men.
Generally, jinn are peaceable and well disposed toward men. Many a pre-Islamic poet was believed to have been inspired by good jinn, but there are also evil jinn, who contrive to injure men.
Those in the Hebrew Bible are of two classes, the se'irim and the shedim. The se'irim ("hairy beings"), to which some Israelites offered sacrifices in the open fields, are satyr-like creatures, described as dancing in the wilderness , and which are identical with the jinn, such as Dantalion, the 71st spirit of Solomon. (But compare the completely European woodwose.) Possibly to the same class belongs Azazel, the goat-like demons of the wilderness, probably the chief of the se'irim, and Lilith . Possibly "the roes and hinds of the field", by which Shulamit conjures the daughters of Jerusalem to bring her back to her lover , are faunlike spirits similar to the se'irim, though of a harmless nature.
Some benevolent shedim were used in kabbalistic ceremonies (as with the golem of Rabbi Yehuda Loevy), and malevolent shedim (mazikin, from the root meaning to damage) are often responsible in instances of possession. Instances of idol worship were often the result of a shed inhabiting an otherwise worthless statue; the shed would pretend to be a God with the power to send pestilence, although such events were not actually under his control.
In some rabbinic sources, the demons were believed to be under the dominion of a king or chief, either Asmodai  or, in the older Haggadah, Samael ("the angel of death"), who kills by his deadly poison, and is called "chief of the devils". Occasionally a demon is called "satan": "Stand not in the way of an ox when coming from the pasture, for Satan dances between his horns" .
According to some texts, the queen of demons is Lilith, pictured with wings and long flowing hair, and called the "mother of Ahriman" . "When Adam, doing penance for his sin, separated from Eve for 130 years, he, by impure desire, caused the earth to be filled with demons, or shedim, lilin, and evil spirits."
Demonology never became an essential feature of Jewish theology. The reality of demons was never questioned by the Talmudists and late rabbis; most accepted their existence as a fact. Nor did most of the medieval thinkers question their reality. Only rationalists like Maimonides and Abraham ibn Ezra, clearly denied their existence. Their point of view eventually became the mainstream Jewish understanding.
Rabbinical demonology has three classes of demons, though they are scarcely separable one from another. There were the shedim, the mazziḳim ("harmers"), and the ruḥin ("spirits"). Besides these there were lilin ("night spirits"), ṭelane ("shade", or "evening spirits"), ṭiharire ("midday spirits"), and ẓafrire ("morning spirits"), as well as the "demons that bring famine" and "such as cause storm and earthquake" (Targ. Yer. to Deuteronomy xxxii. 24 and Numbers vi. 24; Targ. to Cant. iii. 8, iv. 6; Eccl. ii. 5; Ps. xci. 5, 6.)
"Demon" has a number of meanings, all related to the idea of a spirit that inhabited a place, or that accompanied a person. Whether such a daemon was benevolent or malevolent, the Greek word meant something different from the later medieval notions of 'demon', and scholars debate the time in which first century usage by Jews and Christians in its original Greek sense became transformed to the later medieval sense. It should be noted that some denominations asserting Christian faith also include, exclusively or otherwise, fallen angels as de facto demons; this definition also covers the "sons of God" described in Genesis who abandoned their posts in heaven to mate with human women on Earth before the Deluge .
In the Gospel of Mark, Jesus casts out many demons, or evil spirits, from those who are afflicted with various ailments. Jesus is far superior to the power of demons over the beings that they inhabit, and he is able to free these victims by commanding and casting out the demons, by binding them, and forbidding them to return. Jesus also lends this power to some of his disciples, who rejoice at their new found ability to cast out all demons.
By way of contrast, in the book of Acts a group of Judaistic exorcists known as the sons of Sceva try to cast out a very powerful spirit without believing in or knowing Jesus, but fail with disastrous consequences. However Jesus himself never fails to vanquish a demon, no matter how powerful (see the account of the demon-possessed man at Gerasim), and even defeats Satan in the wilderness (see Gospel of Matthew).
There is a description in the Book of Revelation 12:7-17 of a battle between God's army and Satan's followers, and their subsequent expulsion from Heaven to earth to persecute humans — although this event is related as being foretold and taking place in the future. In Luke 10:18 it is mentioned that a power granted by Jesus to control demons made Satan "fall like lightning from heaven."
The contemporary Roman Catholic Church unequivocally teaches that angels and demons are real personal beings, not just symbolic devices. The Catholic Church has a cadre of officially sanctioned exorcists which perform many exorcisms each year. The exorcists of the Catholic Church teach that demons attack humans continually but that afflicted persons can be effectively healed and protected either by the formal rite of exorcism, authorized to be performed only by bishops and those they designate, or by prayers of deliverance which any Christian can offer for themselves or others.
Building upon the few references to daemons in the New Testament, especially the visionary poetry of the Apocalypse of John, Christian writers of apocrypha from the 2nd century onwards created a more complicated tapestry of beliefs about "demons" that was largely independent of Christian scripture.
At various times in Christian history, attempts have been made to classify these beings according to various proposed demonic hierarchies.
According to most Christian demonology demons will be eternally punished and never reconciled with God. Other theories postulate a Universal reconciliation, in which Satan, the fallen angels, and the souls of the dead that were condemned to Hell are reconciled with God. This doctrine is today often associated with the Unification Church. Origen, Jerome and Gregory of Nyssa also mentioned this possibility.
In contemporary Christianity, demons are generally considered to be angels who fell from grace by rebelling against God. However, other schools of thought in Christianity or Judaism teach that demons, or evil spirits, are a result of the sexual relationships between fallen angels and human women. When these hybrids (Nephilim) died they left behind disembodied spirits that "roam the earth in search of rest" (Luke 11:24). Many non-canonical historical texts describe in detail these unions and the consequences thereof. This belief is repeated both in the Koran and other major ancient religions and mythologies. Christians who reject this view do so by ascribing the description of "Sons of God" in Genesis 6 to be the sons of Seth (one of Adam's sons).
There are some who say that the sin of the angels was pride and disobedience, these being the sins that caused Satan's downfall (Ezek. 28). If this be the true view, then we are to understand the words, "estate" or "principality" in Deuteronomy 32:8 and Jude 6 ("And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.") as indicating that instead of being satisfied with the dignity once for all assigned to them under the Son of God, they aspired higher.
Islam recognizes the existence of the jinn. Jinns are not the "genies" of modern lore, and they are not all evil, as demons are described in Christianity, but as creatures that co-exist with humans. In Islam the evil jinns are referred to as the shayātīn, or devils, and Iblis (Satan) is their chief. Iblis was the first Jinn who disobeyed Allah. According to Islam, the jinn are made from the fire (whereas angels are made from light and mankind is made from altered clay).
Adam was the first man, and man was the greatest creation of Allah. Iblis could not stand this, and refused to acknowledge a creature made of "dirt" (man). Allah condemned Iblis to be punished after death eternally in the hellfire. Allah had created hell.
Iblis asked Allah if he may live to the last day and have the ability to mislead mankind and jinns, Allah said that Iblis may only mislead those whom have forsaken Allah. Allah then turned Iblis's countenance into horridness and condemned him to only have powers of trickery.
The word "genie" comes from the Arabic jinn. This is not surprising considering the story of `Alā' ad-Dīn, (anglicized as Aladdin), passed through Arabian merchants en route to Europe.
Hindu mythology include numerous varieties of anthropomorphic beings that might be classified as demons, including Rakshasas (belligerent, shapechanging terrestrial demons), Asuras (demigods), Vetalas (bat-like spirits), and Pishachas (cannibalistic demons).
Originally, Asura, in the earliest hymns of the Rig Veda, meant any supernatural spirit—good or bad. Hence even some of the devas (demigods), especially Varuna, have the epithet of Asura. In fact, since the /s/ of the Indic linguistic branch is cognate with the /h/ of the Early Iranian languages, the word Asura, representing a category of celestial beings, became the word Ahura (Mazda), the Supreme God of the monotheistic Zoroastrians. But very soon, among the Indo-Aryans, Asura came to exclusively mean any of a race of anthropomorphic but hideous demons. All words such as Asura, Daitya (lit., sons of the demon-mother "Diti"), Rakshasa (lit. from "harm to be guarded against") are translated into English as demon. These demons are inherently evil and are in a constant battle against the demigods. Hence in Hindu iconography, the gods and demigods are shown to carry weapons to kill the asuras. Unlike Christianity, the demons are not the cause of the evil and unhappiness in present mankind (which occurs on the account of ignorance from recognizing one's true self). In later Puranic mythology, exceptions do occur in the demonic race to produce god-fearing Asuras like Prahalada. Also, many Asuras are said to have been granted boons from one of the members of the Hindu trinity, viz., Brahma, Vishnu and Shiva when the latter had been appeased from penances. All Asuras, unlike the devas, are said to be mortals (though they vehemently wish to become immortal). Many people metaphorically interpret these demons as manifestations of the ignoble passions in human mind.
On the account of the Hindu theory of reincarnation and transmigration of souls according to one's Karma, other kinds of demons can also be enlisted. If a human does extremely horrible and sinful karmas in his life, his soul (Atman) will, upon his death, directly turn into an evil ghostly spirit, many kinds of which are recognized in the later Hindu texts. These demons could be Vetalas, Pishachas, Bhūtas etc.