Between 40,000 and 60,000 people died in the witch hunts of the Early Modern period. Three developments in Christian doctrine contributed: 1) a return to belief in witches, 2) changes in the doctrine of Satan, 3) the identification of witchcraft as heresy.
Mainstream medieval Christian teaching denied the existence of witches and witchcraft, as mere pagan superstition.   Examples include an Irish synod in 800,  Agobard of Lyons,  Hrabanus Maurus, the Canon Episcopi edited by Regino of Prüm, the Council of Anse, Buchard of Worms, John of Salisbury, Pope Gregory VII,  and Serapion of Vladimire.  The traditional charges and punishments were likewise condemned. 
Christian influence failed to eradicate traditional beliefs, and later developments in the doctrine of Satan proved influential in reversing the previous dismissal of witches and witchcraft as superstition. These beliefs became included in a comprehensive doctrine of Satan,   but it was not until maleficium was identified with heresy that religious trials for witchcraft could start.
Doctrinal change was completed in the fifteenth century,  and new trials started.   Their promotion by Henricus Institoris met resistance in some areas, and his ‘Malleus Maleficarum’ was less influential than previous scholars once believed. 
 Fifteenth to eighteenth century.
 ‘One of the most persistent features of European world views, as we shall see, was the presence of humans who used magic to help or hurt their neighbours.’, Thurston, ‘Witch, Wicce, Mother Goose: The Rise and Fall of the Witch Hunts in Europe and North America’, p. 15 (2001).
 ‘The earliest law codes issued by the northern invaders of the Roman Empire specify penalties for women who were believed to go abroad at night and destroy men by magic.’, Hutton, ‘The Pagan Religions of the Ancient British Isles’, p. 257 (1993).
 ‘Then these clauses were revoked, often explicitly at the insistence of churchmen. The Lombard code of 643 may serve as an example: ‘Let nobody presume to kill a foreign serving maid or female slave as a witch, for it [destruction by magic] is not possible, nor ought to be believed by Christian minds. In 789 Charlemagne imposed Christianity upon the people of Saxony, and proclaimed to them: ‘If anyone, deceived by the Devil, shall believe, as is customary among pagans, that any man or woman is a night-witch, and eats men, and on that account burn that person to death . . . he shall be executed.’12 Thus it might be argued that the spread of Christianity initially resulted in an improvement in the treatment of both religious dissenters and alleged witches.”, ibid., p. 257.
 ‘Likewise, the Lombard King Rothari (c. 606-52) decreed in 643 that Christians must not believe that women devour a human being from inside (ut mulier hominem vivum instrinsecus possit comedere), and therefore supposed witches (strigae) must not be killed, particularly not convicted in court.’, Behringer, ‘Witches and Witch-hunts: a Global History’, p. 30 (2004).
 ‘Indeed, in those parts of western Europe which were the home of, or taken over by, Germanic tribes, it seems that the Church ended a tradition of hunting and killing witches.’, Hutton, ‘The Pagan Religions of the Ancient British Isles”, p. 257 (1993).
 ‘Certainly the early Church cannot be held responsible for the mass burnings of heretics which commenced seven centuries after its installation in power, or the great witch hunt which began eleven centuries later. During that long interval, Christendom itself changed.’, ibid., p. 257.
 ‘Clearly, there was an increase in sceptical voices during the Carolingian period, even if we take into account an increase in surviving sources.’, Behringer, ‘Witches and Witch-hunts: a Global History’, p. 31 (2004).
 ‘Likewise, an Irish synod at around 800 condemned the belief in witches, and in particular those who slandered people for being lamias (que interpretatur striga).’, ibid., pp. 30-31.
 ‘A Crown witness of ‘Carolingian scepticism’, Archbishop Agobard of Lyon (769-840), reports witch panics during the reign of Charlemagne. In his sermon on hailstorms he reports frequent lynchings of supposed weather magicians (tempestarii), as well as of sorcerers, who were made responsible for a terrible livestock mortality in 810. According to Agobard, the common people in their fury over crop failure had developed the extravagant idea that foreigners were secretly coming with airships to strip their fields of crops, and transmit it to Magonia. These anxieties resulted in severe aggression, and on one occasion around 816, Agobard could hardly prevent a crowd from killing three foreign men and women, perceived as Magonian people. As their supposed homeland’s name suggests, the crop failure was associated with magic. The bishop emphasized that thunderstorms were caused exclusively by natural or divine agencies.’, ibid., pp. 54-55.
 ‘Hrabanus Maurus, Abbot of Fulda, wrote several attacks, including ‘On the magical arts’, much of which was derived from Isidore of Seville, on those who believed that magicians and sorcerers could accomplish anything that depended on their power alone.’, Jolly, Raudverre, & Peters, ‘Witchcraft and Magic in Europe: the Middle Ages’, p. 201 (2002).
 ‘One of the most important ecclesiastical documents of the Middle Ages was the Canon Episcopi, ca. 900, which defined witchcraft as Devil-worship, but declared it to be nothing more than a foolish idea.’, Guiley, ‘The Encyclopedia of Witches, Witchcraft, and Wicca’, p. 50 (2008).
 ‘Witchcraft beliefs however were not always endorsed by the upper levels of society. They were condemned as superstitious by the Council of Anse in 990 and by Buchard of Worms a few years after, as when John of Salisbury dismissed them as the imaginings of ‘a few poor men and ignorant women, with no real faith in God.’, Moore, ‘The Formation of a Persecuting Society: Authority and Deviance in Western Europe 950-1250 ‘, p. 133 (2007).
 ‘In 1080 Harold of Denmark (r. 1076-80) was admonished not to hold old women and Christian priests responsible for storms and diseases, or to slaughter them in the cruellest manner. Like Agobard before him, Pope Gregory VII (r. 1073-85) declared in his letter to the Danish king that these catastrophes were caused by God alone, that they were God’s punishment for human sins, and that the killing of the innocent would only increase His fury.”, ibid., p. 55.
 ‘Witches were executed at Novgorod in 1227, and after a severe famine in the years 1271-4 Bishop Serapion of Vladimire asked in a sermon: ‘you believe in witchcraft and burn innocent people and bring down murder upon earth and the city… Out of what books or writings do you learn that famine in earth is brought about by witchcraft?‘, ibid., p. 56.
 ‘A capitulary of Charlemagne (747-814) for the Saxons in 787 imposed the death penalty on those who, like pagans, believed that a man or woman could be a striga, one who devours humans, and burned them.”, ibid., p. 30.
 ‘A decree of King Coloman of Hungary (c. 1074-116, r. 1095-1116) against the belief in the existence of strigae (De strigis vero que non sunt, ne ulla questio fiat) suggests that they were thought to be human beings with demonic affiliation: witches.’, ibid., p 32.
 Study after study has shown how, all over Europe, ordinary people regularly appealed not to their own consciences, or to the conscience of the Church, but to local practitioners skilled in healing, divination, and astrology for help with their everyday problems. They did this frequently in cases of suspected maleficium, but any kind of misfortune, anticipated or experienced, could justify a visit to the ‘cunning’ man or woman.’, Clark, ‘Thinking With Demons: the Idea of Witchcraft in Early Modern Europe’, p. 457 (1999).
 ‘Early Christian theologians attributed to the Devil responsibility for persecution, heresy, witchcraft, sin, natural disasters, human calamities, and whatever else went wrong. One tragic consequence of this was a tendency to demonize people accused of wrongs. At the instance of ecclesiastical leaders, the state burned heretics and witches, burning symbolizing the fate deserved by the demonic.’, Hinson, ‘Historical and Theological Perspectives on Satan’, Review and Expositor (89.4.475), (Fall 1992).
 ‘Trevor-Roper has said that it was necessary for belief in the Kingdom of Satan to die before the witch theory could be discredited.’, Larner, ‘Crime of Witchcraft In Early Modern Europe’, in Oldridge, ‘The Witchcraft Reader’, p. 211 (2002).
 ‘Christian theology underwent a major shift of attitude only during the thirteenth century. In his Summa contra Gentiles, Thomas Aquinas (1255-74) not only confirmed Augustine’s semiotic theory, according to which spells, amulets or magical rituals indicated a secret pact with demons, but gave the impression that sorcerers, through the support of the devil, could physically commit their crimes.’, Behringer, ‘Witches and Witch-hunts: a Global History’, pp. 35-36 (2004).
 ‘Sorcery was, however, still subject to secular law and secular courts, since the main indictment was maleficium. Subsequent inquisitors like Nicolas Eymeric (c. 1320-99), inquisitor of Aragon, in his Directorium Inquisitorum of 1376 equated sorcerers with heretics because both were supposed to adore the devil. Sorcery, or witchcraft, was thus redefined as a spiritual crime, subject primarily to ecclesiastical courts, and the Inquisition in particular.’, ibid., p. 36.
 ‘We are reasonably confident today that the ‘classical’ doctrine of witchcraft crystallized during the middle third of the fifteenth century’, ibid., pp. 18-19.
 ‘By the end of the fifteenth century, scattered trials for witchcraft by both secular and ecclesiastical courts occurred in many places from the Pyrenees, where the Spanish Inquisition had become involved, to the North Sea.’, ibid., p. 19.
 ‘In Switzerland, the rustic ‘forest cantons’ of the original Confederation apparently remained unaffected by witch trials until after 1560.’, Behringer, ‘Witches and Witch-hunts: a Global History’, p. 19 (2004).
 ‘the first known witch-hunt in the kingdom of France began in the northern Pyrenees in the spring of 1562’, ibid., p. 21.
 ‘Germany was emphatically not the centre of this activity; Institoris encountered enormous hostility in the Austrian Alps, and absolutely no evidence exists that the publication of his Malleus started any chain of trials anywhere in the Empire.’, ibid., p. 19.
 ‘In its own day it was never accorded the unquestioned authority that modern scholars have sometimes given it. Theologians and jurists respected it as one among many informative books; its particular savage misogyny and its obsession with impotence were never fully accepted.’, Monter, ‘The Sociology of Jura Witchcraft’, in ‘The Witchcraft Reader’, p. 116 (2002)
 ‘The effect that the book had on witch-hunting is difficult to determine. It did not open the door ‘to almost indiscriminate prosecutions’ 50 or even bring about an immediate increase in the number of trials. In fact its publication in Italy was followed by a noticeable reduction in witchcraft cases.’, Levack, ‘The Witch-Hunt In Early Modern Europe’, p. 55 (2nd edition 1995).