In the teachings and traditions of all world religions, demons are spiritual entities without physical bodies that roam the Earth seeking to torment whomever attracts them through a wide variety of means—from weakness to wizardry. According to these ancient traditions, demons have supernatural powers; they are numerous; and they are organized. They can inflict sickness and mental disorders on their victims. They can possess and control humans and animals. Demons lie and deceive and teach false and misleading doctrines of spirituality. They oppose all teachings and actions that seek to serve the good and God.
According to the great teachers of the world religions, the main tasks of demons are to disseminate error among humans and to seduce believers into forsaking good for evil. Since they are such skilled deceivers, it is nearly impossible to develop an adequate litmus test that will unfailingly distinguish between good spirits and bad ones. Unless one is truly pure in heart, mind, and soul and has the ability to maintain only clean thoughts and good habits, it is very difficult to discern with unfailing accuracy the true nature of demon spirits. 
Theologians remind their followers that as mortal beings they are in the midst of a great spiritual warfare between the angels of light. 
who serve God and the fallen angels who serve the forces of darkness—and that their souls may be the prize for the victors. Accomplished spiritual teachers of all faiths advise their congregants that the good spirits will never try to interfere with the free will of humans or seek to possess their bodies. On the other hand, the evil spirits desire the physical host body of a human being. In fact, they must have such a vehicle if they are to experience earthly pleasures. When a demon invades a human body, it is said that possession has occurred and an exorcism by a priest or shaman may be required to free the victim from the evil spirit’s grasp.
Demonic entities are credited with will and intellect, but these attributes are invariably directed toward evil as they exert their malevolent powers. When these evil spirits penetrate the material world and the circumstances of human life, they conceal themselves in every aspect of human existence. 
In many instances, the gods of the old religions become the demons of the new. The Asuras, a race of gods in the early Vedas (sacred Hindu texts composed around 1500 to 1200 B.C.E.), are transmuted to powerful evil beings with the advent of the new deities of Indra and Vishnu. The raksasas are a class of entities who attack humans with the intended goal of driving them insane or causing them material ruin. As in many theologies, there is an ambivalence concerning certain deities. In Hinduism, the most terrifying of the gods, such as Kali, Durga, and Shiva, although seemingly demonic and destructive, often perform deeds that ultimately turn out to be good.
In the scriptures of the world religions, the chief of the legions and hordes of demons is known by various names: Satan, Lucifer, Iblis, Mara, and Angra Mainyu, among others. The word “devil” is derived from the Greek diabolos, which means “accuser” or “slanderer,” and is one of the names for Satan. Daimon, the Greek word from which “demon” is derived, originally meant a tutelary spirit or a spirit guide, but it is frequently, and incorrectly, translated as “devil” or “demon.” In the traditions of Christianity, Islam, and Judaism, the animosity between demons (the fallen angels) and the human race can be traced to the moment when God granted his
earthly creations of dust and clay with the priceless gift of free will. In the biblical and qur’anic traditions are found references to the jealousy that afflicted certain angels regarding the attention that God displayed toward his human creation. In the Qur’an (17:61–64), Iblis (Satan), the leader of the rebellious angels, refuses to bow to a creature that God has created of clay, and he threatens to make existence miserable for the descendants of the being that the Creator has honored above them. Because of the declared animosity of the fallen angels against those heavenly beings who remain faithful to the Creator and against those mortals who seek to follow the higher teachings of revealed truth, the epistle writer Paul (d. 62–68 C.E.) gave counsel when he warned that humans not only engage in spiritual warfare with those of flesh and blood who serve evil, “but against the principalities, against the powers, against the world rulers of this present darkness, against the spiritual hosts of wickedness in the heavenly places” (Ephesians 6:12).
Although Buddhism generally rejects a cosmological dualism between good and bad, angels and demons, there is an aspect within the traditional lives of the Buddha which echoes the jealousy motif of various entities toward humans. Mara, who tempted the Awakened One on the night of his enlightenment, is said to be an asura or a Deva (a being of light) who was jealous of the power that was about to be bestowed on a human, for to become a Buddha would be to achieve spiritual status greater than they possessed. Tibetan Buddhism borrows its demons from Hinduism and adds a number of indigenous entities, who are ambivalent toward the inhabitants of the Himalayas, sometimes appearing as fierce and malevolent creatures, other times manifesting as teachers of enlightenment.
Various scriptures state firmly that regardless of their strength, power, and majesty, angels are not to be worshipped, and religious teachers advise that true heavenly beings will immediately discourage any humans from attempting to bow their knees to them. On the other hand, the fallen angels, the demons, are motivated by their own selfish goals and delight in corrupting humans. They encourage mortals to express greed and to seek the acquisition of material, rather than spiritual, treasures. As a general spiritual law, these negative entities cannot achieve power over humans unless they are somehow invited into a person’s private space—or unless they are attracted to an individual by that person’s negativity or vulnerability.


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