The study investigates the witchcraft persecution in the United Kingdoms of Denmark and Norway in the 17th century. The paper is delimited to deal with the reign of King Christian the Fourth, when the witchcraft persecution of Denmark-Norway had its climax and the legislation of witchcraft was intensified. With the use of mentality history, the pivotal point for this study is to find an answer to the basis for doing those witchcraft persecutions. Through an analysis of the four most essential society instances, the Peasants, the Church, the King and the Legislation, the goal is to picture the mentality of that time, and through that, clarify the basis of the witchcraft persecution. The study in particular highlights, Finmarken, the limit of the United Kingdoms, which in this period was one of the places, considered the population, where the witch hunting was most extensive, compared to the rest of Europe. From preserved legal sources, it has been possible to estimate that the risk of gaining sentence on witchcraft crime was 28 times bigger in Finmarken, than it was in Denmark in that time, despite the fact that Denmark and Norway, were unified in a double monarchy under the reign of the same king. Therefore the study also attempts to attain an explanation for this paradox. Throughout the analyses, the prime focus is how the four society instances separately understand and relate to the phenomenon of witchcraft. Among the peasants it appears that the Christian faith stood side by side with the superstition. The peasants’ conception of witchcraft and magic was far more differentiated than the church’s. The church thought that all types of magic were a sin. This stood in contrast with the peasants, who distinguished between black and white magic. The peasants regarded magic and rituals of protection as an integrated part of the everyday life. In addition, the magic worked as a good supplement to the power of God. Furthermore, the witchcraft also contributed to some kind of explanation for inexplicable phenomena. The witchcraft legislation wasn’t something new. As early as the introduction of Christianity, people had become aware of the phenomenon of witchcraft. But after the Reformation all legal actions about witchcraft became subject to the secular power. Thus, the church was disposed of the jurisdiction, but nevertheless the clergy obtained even more influence during the witchcraft persecutions. The clergy still had a powerful position, and the clergyman still played a crucial part in the local community. During the 16th century, the witchcraft legislation got more multi-faceted, which reached its peak with the 1617 order of King Christian the Fourth. Through a more developed government and a more stringent legislation, the whole social organization underwent a sweeping mobilization, with the goal of stamping out the sin. The analyses of the study all unify in one superior discussion about the main reason behind the 17th centuries witchcraft persecution, and the basis of the massive persecutions in Finmarken. Finally, the study concludes that the witchcraft persecutions of the 17th century arose from the conflict between on the one hand the inherited common idea, and on the other hand, the wish of the élite to modernize and control the society. The demonological ideas of the church in addition to the central power’s indirect strategy of colonization in connection with the build of the Lutheran princely state must be seen as the main parameter of explanation in relation to the massive witchcraft persecutions in Finmarken. The Sami people of the north of Norway posed a security risk, and for that reason they were seen as the interior enemies of the kingdom. The massive persecutions in Finmarken are, therefore concluded to be a parallel result of the expansion of the United Kingdoms of Denmark-Norway in the 17th century.