The Protestant Reformation, despite often being associated with the symbolic figure of Martin Luther nailing his 95 Theses to the door of the Castle Church in Wittenberg on October 31, 1517, cannot be reduced to a single, abrupt, and exceptional event. Rather, it must be traced to a much longer process of spiritual, social, and intellectual transformation that unfolded over the late medieval period. This historiographical perspective acknowledges the deep-rooted need for a Reformation, transforming the period between the 14th and 16th centuries into a genuine "Age of Reformation." Authors such as Eric Leland Saak emphasize that criticisms of ecclesiastical authority and calls for reform (sola scriptura) were already evident in the preceding centuries. In fact, reformers John Wycliffe and Jan Hus, who lived several decades before Luther, anticipated central themes of the Reformation, laying the foundations for a critique, making Luther's actions not the beginning of a secular movement but the culmination of it.

Although the Reformation began in Germany, it spread and developed quickly throughout Europe in unique ways, fueled by conflicts and disagreements between European courts, the clergy, and the papacy. It's also necessary to focus on Northern European countries where the Reformation had significant political consequences, such as Scandinavia and parts of Eastern Europe (e.g., Hungary and Transylvania). In Scandinavia, the events in Wittenberg were the main inspiration for the Reformation, but its adoption varied considerably. In the Danish Kingdom, it was quickly established, while Sweden had become de facto Lutheran by 1550. In peripheral areas such as Norway and Iceland, it was reluctantly accepted and was linked to closer political integration.