From their airy habitat Satan and his demons wage incessant war upon the Christians. That is how Paul imagines them;(28) and the Fathers expatiate at length on the various ways in which they persecute the new faith and its adherents. For the Devil, who never knows peace, cannot leave men in peace;(29) together with his demons he causes both the sickness of individuals(30) and collective disasters such as drought, bad harvests, epidemics amongst men and beasts.(31) Moreover the demons have now devised new ways to afflict the Church. On the one hand they inspire Roman officialdom to persecute Christians,(32) and on the other hand they seduce Christians to abandon the true faith, to fall into schism and heresy.(33) St Cyprian even holds that but for the activity of devils there would be no heresies or schisms at all.(34)
For the Fathers, as for Paul, the demons are also present in the deities of the ancient world. As they see it, if a Christian ventures to criticize new practices or beliefs, after they have received the official sanction of the Church, this must be instigated by a pagan deity, operating as a demon. When a monk called Vigilantius writes against the growing cult of the bones of the martyrs, Jerome retorts: “The unclean spirit who makes you write these things has often been tormented by this humble dust (of the bones of the martyrs). . Here is my advice to you. Go into the basilicas of the martyrs, and you will be cured. Then you will confess, what you now deny, that it is Mercury who speak through the mouth of Vigilantius.”(35) The surest proof of the truth of Christianity lies in the ability of Christians to exorcize demons from the human beings whom they have possessed; for each such exorcism represents a victory of Christ over a pagan deity. This is the view of Tertullian and Cyprian early in the third century,(36) and it is still the view of Sulpicius Severus in his life of St Martin of Tours, written early in the fifth century: “Each time Martin came to the church, the demoniacs who were there howled and trembled as criminals do when the judge arrives. . When Martin exorcized the demons. . the wretched demons expressed in various ways the constraint they were under. . One would admit he was Jupiter, the other Mercury.”(37)
Satan’s greatest offence, in fact, lay in the persistence of the pagan religion itself; for all who adhered to it were in effect worshipping demons. Such an interpretation of the ritual of Graeco-Roman religion is like a foretaste of those fantasies of Satan-worship which medieval clerics were to weave around the activities of dissenting sects, a thousand years later.
Nevertheless, the similarities between early Christian and medieval Christian attitudes should not be exaggerated. The atmosphere of morbid fascination which fills the medieval descriptions is quite lacking in the polemics of the early Fathers; and it is easy to see why. In the days of the Fathers the Church was still full of optimism, still sure of its faith and of the triumph of that faith. Satan might be strong, but it was within the power of any Christian to resist him. The work known as The Shepherd of Hermas, which dates from the first half of the second century, is emphatic on the point: he who fears God cannot be affected by the Devil; Satan himself takes flight when he comes up against strong resistance, so only those without the Christian faith need fear him.(38) In the second half of the second century Irenaeus maintains that the Devil flees before the prayers of Christians,(39) while Tertullian is convinced that it is enough simply to pronounce the name of Christ.(40) If God allows demons to tempt a Christian, it is in order that the Christian may put them to shame and at the same time strengthen his own faith. And in Origen’s view the power of Satan and his hosts is already declining; each time a demon is successfully resisted by a Christian, he is thrust into hell and loses the right to tempt. As a result, the number of demons on active service is diminishing, the power of the pagan gods dwindles, and pagans find it ever easier to become Christians.(41)
This sublime self-confidence still inspired the Church which christianized the Germanic and Celtic peoples of Europe. But gradually over the centuries new and terrible anxieties began to make themselves felt in Christian minds, until it came to seem that the world was in the grip of demons and that their human allies were everywhere, even in the heart of Christendom itself.
Satan and his demons, as they were known to the early Christians, were already products of a long and complex evolution; and they continued to change during the following centuries. By the later Middle Ages they had become far more powerful and menacing, and they were also far more closely involved in the lives of individual Christians.
They also shed their ethereal bodies. As early as the fifth century, the religious philosopher known as Pseudo-Dionysius or the Pseudo-Areopagite propounded the theory that the angels were purely spiritual beings, organized in an elaborate hierarchy; and the same applied to fallen angels, or demons. The book containing these speculations, entitled The Celestial Hierarchy, was translated from Greek into Latin by Joannes Scotus Erigena in the ninth century; and in the twelfth century the mystic Hugh of St Victor, in Paris, wrote a commentary on it, in which he argued powerfully for the absolute spirituality of the demonic as of the angelic hosts. Hugh’s disciple, Richard of St Victor, pointed out that if, as is stated in the New Testament, a man can contain a legion of demons, demons must indeed be incorporeal, for a legion comprises 6,666 individuals. The great scholastics followed in the footsteps of these mystics, until in the thirteenth century St Thomas Aquinas established the spiritual nature of angels and demons as an unshakeable part of Roman Catholic doctrine.
Yet these speculations were of limited relevance, for demons retained their capacity to take on a bodily form at will. Early in the fifth century Jerome insisted that demons were able to take on grotesque forms, and to be seen, heard and felt by human beings. About the same time the ecclesiastical historian Theodoret told how in the preceding century Bishop Marcellus of Apamea in Syria had tried to burn down a temple of Jupiter; he was constantly impeded by a black demon, who kept extinguishing the fire.(42) Around 600 Pope Gregory the Great introduced Satan or some lesser devil into many of his stories about monks and bishops. He describes, for instance, the curious adventure of a Jew who happened one night to find himself in a temple of Apollo. A throng of demons were in the temple, and they were reporting to their leader on the various tricks they had played on pious Christians. One of them had even induced a bishop to pat a nun tenderly on her back.(43) The biography of St Afra, which belongs to the period between 700 and 850, already shows Satan in the form that was to become standard in the later Middle Ages: pitch-black, naked and covered with a wrinkled skin.(44)