Devil, or Satan, the names applied in the New Testament and in Christian theology to the supreme impersonation of evil, considered as possessing an objective existence outside of man, and placed at the head of a host of inferior evil spirits, whose continual occupation is to thwart the good purposes of God and the progress of his kingdom in the hearts of men. Other names merely suggest the same essential ideas of his nature and function, as the wicked one, the enemy, and the like. It seems certain that this conception was foreign to the early Jewish mind, with its strong grasp of the monotheistic idea in the person of the supreme Jehovah. It is Jehovah himself who hardens Pharaoh's heart, and sends a lying spirit among the prophets of Ahab, and it is he who is considered as the sole source of all power, the sender of pestilence and death as well as blessings. In the exegesis of later days the serpent that tempted Eve in Eden, and the 'Old Serpent' of the Apocalypse, were alike identified with Satan, although this interpretation certainly gains no support from the story in Genesis, where the tempter is as yet hardly more than a mere animal, although one of a family almost everywhere specially associated with evil.
It is significant that the name Satan occurs but five times in the Old Testament: thrice in Job, where he presents himself among the 'sons of God' (Beni Elohim) before the Lord. Here he is the willing messenger of evil, but yet he is not represented as Job's spiritual enemy, nor yet as a distinct impersonation of evil. He is hardly more than an agent of one form of divine providence, by whose means Job is tried and lifted into a higher spiritual plane, and his energies hardly range out of the region of mere physical into that of moral evil. The Beni Elohim throughout are employed as the messengers of Jehovah, and carry out his mercies and punishments alike, both bearing messages of consolation and promise to the patriarchs, and filling Saul's mind with gloomy thoughts, appearing with drawn sword to Balaam, or destroying in one night a whole Assyrian host. The Jews had also their demonology like all primitive peoples, as may be seen in the seirim (satyrs, lit. 'he-goats') and the shedim, both rendered by 'devils' in the authorised version, and perhaps also in the Azazel of Leviticus xvi.; but it was not till later that a special angel became differentiated from his brethren in the heavenly court, with the special function of the accuser of men, like the personification of a guilty conscience. In the vision of Zechariah we find him considered formally as the accuser of Israel. Undoubtedly also this conception had already become greatly modified during the period of exile by contact with Persian dualism. Of course such a conception as Ahriman, the mighty author of evil and the antagonist almost on equal terms of
Ormuzd, was completely foreign to Jewish monotheism, yet the Jewish Satan grew greatly both in definiteness and in power under his shadow, and henceforth it is from him directly that moral and physical harm towards men proceeds. Yet it must not be supposed that this was due to direct borrowing, and that the Jewish Satan was not substantially an original evolution of the native Jewish mind. 'While Ahriman is physical evil that has become moral evil also,' says M. Réville, 'Satan is moral evil becoming physical evil.'
Persian influence appears most plainly in the apocryphal books of Tobit and Baruch, but the growth of the conception of the devil is seen also in the translation of the LXX., which renders his name by diabolos, thus emphasising and perpetuating his special function as the accuser. Now also he becomes located in his gloomy kingdom of hell, and is attended by troops of inferior fiends. He wages warfare on mankind by inflicting physical and moral evil, and is considered as the agent by whose means man fell from his original state of innocence. It was thus he who introduced death with all its horrors into the world, and consequently diseases, especially those of greater violence and obscurity, are the work of himself or his minions.
In the New Testament the conception of the personality of the devil and of a kingdom of demons holds its ground, but the whole subject is here treated with a kind of spiritual reserve, in a teaching that emphasises our own hearts and their inward temptations as the source of our evil thoughts and deeds, and connects moral evil inseparably with the earthly nature of man. The passages which speak of a fall of angelic beings (2 Peter, ii. 4; Jude 6) occur in scriptures of subordinate canonical rank; Jesus nowhere defines concretely the function of the devil; and the few positive statements about him—that 'he was a murderer from the beginning, and stood not in the truth,' that 'he is a liar' (John, viii. 44), and 'sineth from the beginning' (1 John, iii. 8), scarcely furnish a sufficient foundation for a complete doctrine on this subject. Yet the impressive manner in which it is dwelt on by our Lord and his apostles shows that it is a necessary part of Christian teaching. The New Testament devil is an enemy of the divine, but yet an inferior and degraded spirit. He is the tempter of man, and even of the Son of God, yet his temptations fall without effect upon upright purity, and through the Saviour's merits the individual Christian is also saved from his power, in spite of all the perilous temptations of his own flesh. Christ's saving work is regarded as the virtual victory over the power of Satan, and the grand drama of the last decisive struggles and final subjugation of the kingdom of the devil forms the conclusion of New Testament prophecy.
The early theologians were more literal and less spiritual in their conceptions, and in their horror of heathen institutions came to identify the kingdom of the devil in a particular manner with polytheism and the persecution they suffered under the Roman empire. Thus the devil again became a kind of rival of God, wholly unequal but yet formidable. The strength of the belief in a powerful personal devil may be seen in the earliest heresies, those of the Gnostics and Manichæans, a main feature in which was an elaborate system of evil demons as enemies to man and almost rivals to God. The early Christians considered the gods of heathenism as indeed conquered by Christ, but yet not rendered wholly powerless, for as degraded demons and with intent to deceive they uttered oracles, and were present at sacrifices, inhaling the sacrificial incense—an idea in perfect harmony with the growing materialistic conception of the devils, and of hell their residence, a place blazing with eternal fire, and filled with every horror the imagination could suggest. The belief in the objective personality of Satan was complete in the literalistic explanation of the 'descent into hell,' and the release of the 'spirits in prison.' It was a literal conquest over an enemy, although by some it was explained almost as if due to superior cunning rather than superior power.
Exaggerated ideas of the devil's dangerous power prevailed throughout the dark and middle ages, whose deep melancholy faith and fantastic theory of the universe generated saints naturally on the one hand, and witches and sorcerers as naturally on the other. It was an involuntary exercise of the poetic faculty, through which the thoughts of their own hearts and of their own time became spirits, which they saw around them. Countless legends were originated of actual contests between individual saints and devils in one or other of a thousand forms. Safety from the devil could be found alone within the charmed ring-fence of the church, fortified by the ordained sacraments and by personal cleanness of life. Excommunication was synonymous with being 'delivered over to Satan,' to whom the popular imagination transferred freely all the lingering remnants of earlier demonologies, so that that particular form and those particular attributes became permanently associated with his appearance which medieval art has fixed and handed down to us. Lechery had ever been a persistent quality of the devil (from the literal interpretation of Gen. vi. 2), and the popular imagination working out this idea gave free play to a fearful but prurient fancy, which revelled in multiplying all the disgusting details of a witches' sabbath. Throughout the middle ages the devil was an absorbing idea, and the constant familiarity with him often brought with it a penalty of contempt. In the old religious plays a principal part was usually assigned to him, and indeed he principally represented the comic element, as may still be seen in the pastorales of the Basques. The auditors might laugh for the moment to see the devil outwitted and then beaten, but they had not shaken off that fear which revenged itself in all the pitiless cruelties of witchcraft—the darkest chapter in the history of humanity.
The decadence of belief in the active external power of the devil was mainly due to the indirect effect of the Reformation and the progress of science. To no man was the devil ever more present than to Luther, but nevertheless it was mainly the movement he inaugurated that has driven the enemy back into the sphere of the abstract and the ideal. In later generations the sense of the supernatural has steadily decayed, and with it almost all the terrors of the devil; but it cannot be said that with it has also disappeared a genuine religious spirit. The Christian man in the conscious weakness of his struggle against indwelling sin feels that he has no need to conjure up for himself an external suggester of temptation—he has devils enough in the treacherous inclinations of his own heart. And in assuming a personal devil to account for the evil side that there is in nature and in life, there remains the question to be answered whether we have not merely pushed back the most puzzling of all questions a single stage, and whether we have contributed at all to the insoluble problem of the genesis of evil.
Kant (in 1793) defined the devil as the personification of 'radical evil.' Schleiermacher held that symbolic reference to the devil might fitly have a place in Christian discourse, but denied the possibility of his real existence, and in this he has been followed by Schenkel, Biedermann, Lipsius,
Pfeiderer, and others. Pfeiderer, estimating the critical result of the doctrine, finds that—whilst a twofold logical contradiction is involved in the idea of devils as the substantial existence of wickedness, and as supra-mundane creatures belonging to this world—devils represent the obverse of religious idealism, or empirical world-existence in its hostility to the Idea; in other words, the world on the side of its opposition to God, or the working for itself of finite and opposing existence as such, presenting itself as the sum and substance of evil. That the two forms of evil—the natural and the spiritual or moral—stand in inward connection, and form a universal (and accordingly metaphysical) power in the world, is the truth contained in the idea of the devil that has significance for the practice of worship. On the other hand the orthodox view is maintained more or less definitely by Lücke, Von Hofmann, Luthardt, Rothe, Julius Müller, Martensen, and Dorner, who holds that though the doctrine cannot be completely constructed, it yet forms part of a consistent whole, and is of importance for the Christian, as distinguished from the heathen and Jewish conception of evil, as well as for the Christian life. See ATONEMENT, DEMONOLOGY, EVIL, EXORCISM, HELL, WITCHCRAFT; also Roskoff's admirable Geschichte des Teufels (1869).