The spread of Christianity in Denmark unfolded gradually, beginning with Viking encounters with Christian populations during raids from the 9th century onwards. Initially, Danes remained rooted in their pagan traditions, with local chiefs determining attitudes toward Christianity. The influx of Christian slaves, captives, and future wives from Viking raids, however, brought Danes into close contact with the faith, planting the seeds of conversion.
As Danish kings and chiefs engaged in the politics of Normandy, England, Ireland, France, and Germany, they began to adopt more favorable attitudes toward Christianity, often for political reasons. The conversion of a chief or king sometimes led to widespread conversions among their followers, but genuine acceptance of Christianity often blended with existing beliefs, showing how deeply entrenched the old ways were.
Christian missionaries adapted to the unique religious landscape in Denmark, where sacred sites often included springs, groves, or hilltops rather than stone idols. They skillfully integrated Christianity by building chapels at these locations, gradually shifting the religious significance from pagan traditions to the Christian faith. The result was a blending of beliefs, where Danes continued practices like leaving offerings to land spirits and consecrating sacred springs to local saints. Even the symbol of Thor's hammer merged seamlessly with the Christian cross.
Gorm the Old, known as the first king of a unified Denmark, ruled from Jelling and was described as "hard and heathen." However, Queen Thyra, his wife, allowed Christians to live without persecution. Their son, Harald Bluetooth, would later play a decisive role in Denmark's Christianization. Harald boasted on the larger Jelling Stone that he had "made the Danes Christian." The inscription on this stone, along with the Latin cross on the Curmsun Disc, suggests that Harald had embraced Christianity by the 960s or 980s. Harald Bluetooth's conversion reportedly occurred after witnessing a Frisian monk named Poppo holding a fire-heated iron without injury, a miraculous event that convinced Harald of Christianity's power. His conversion marked a significant turning point, leading him to baptize his children, Gunhilde and Sweyn Forkbeard, and to move the royal residence from Jelling to Roskilde on Zealand.
By the reign of Canute IV in the early 11th century, Denmark had fully embraced Christianity. Canute IV, who would later become known as St. Canute, was a fervent supporter of the church. His efforts to enforce the tithe and introduce new ecclesiastical structures, however, led to a rebellion in which he was murdered inside St. Alban’s Church in 1086. His subsequent canonization in 1188 signified the ultimate triumph of Christianity in Denmark. The transfer of his remains to Odense Cathedral was a defining moment, with the nation observing a three-day fast, signaling the widespread acceptance of Christianity. This event marked a turning point in Danish history, solidifying the faith's place within the nation.