More than a millennium ago, the Scandinavian Peninsula was a hotbed of religious fervor, the epicenter of a Christian mission to proselytize the so-called "heathen masses." 

With Christian missionaries first coming to Viking societies in late antiquity, the slow process of Christianization took more than five centuries to complete. 

However, the Christianization of Scandinavia would lay the framework for the establishment of the medieval kingdoms of Denmark, Norway, and Sweden.

The early medieval period in Scandinavia - an age of Vikings or of Christians?

Historians and academics that specialize in early medieval European history have often dubbed the period ranging from the late 8th to the early 11th century CE "The Viking Age." 

It is true that warriors, settlers, and traders from Viking societies played an oversized role in this period of European history. However, Vikings hopping on ships to raid Paris, Constantinople, or a plethora of British coastal villages was not the only activity in Scandinavia. 

Religion – in the form of Christianity – was flowing from areas of Europe back to Scandinavia to radically change the peninsula's political, cultural, social, and economic foundations forever.

The Christianization of Scandinavia was a slow process that ran concurrently with the "Viking Age" and would eventually outlast those fierce Viking warriors from the cold North. 

Christian missionaries had first come to Denmark in the 8th century, but it would take more than four centuries, until the end of the 12th century, for the peninsula to be officially converted to Christianity. This Christian mission also helped lay the foundations of the three medieval kingdoms of Denmark, Norway, and Sweden.

Religion in Scandinavia before Christianity

Peoples and societies inhabited the Scandinavian Peninsula for thousands of years with their sets of religious beliefs, practices, and rituals. By the end of the 8th century, people in Viking societies had developed a rich belief system and practices that had stemmed from older Germanic religions. 

Norse paganism (often called the Old Norse religion) was a polytheistic religion with a wide pantheon of gods and goddesses. These gods were not only into two groups – Æsir and the Vanir – eternally at war with each other – but their world was also inhabited by a horde of other mythological creatures, including gnomes, elves, and giants.

There was a heavy emphasis on oral traditions – giving birth to some of the Norse epics that are enjoyed to this day – and relied much less on written works or codified texts. This religion borrowed heavily from surrounding cultures – especially the Samí and Finns – and had significant elements of shamanism, ancestor worship, and ritual practices – including human sacrifices. 

Perhaps the most significant monument to this form of Norse paganism was a great temple at Uppsala, Sweden. This was a center of a cult following and worship until well into the 11th century CE despite Christianity's growing influence in the country.

Further north from the peoples in early medieval societies living in Scandinavia were indigenous peoples, including the Sami and Finns. The Samí – who inhabit a northern area of the Scandinavia peninsula called the Sapmí  - are a people who have lived in this region since at least the Germanic peoples settled further south in the first century CE. 

Their beliefs are based on a mixture of animism, shamanism, and polytheism. One of their most important beliefs was that all of nature – whether an animal or a simple rock in a stream – had a living soul. They also had a strong relationship with local animals and the veneration of their dead.

The Finns, inhabiting northern regions of what is now Finland and Russia, worshipped a number of different deities in their pagan spiritual beliefs, including the god of thunder and sky (Ukko). Their form of beliefs, practices, and ideas seems to be somewhat influenced by the Samí and the Old Norse religion.

The religions and spiritual beliefs practiced by the various people in Scandinavia were sophisticated, entrenched, and diverse before the first Christian missionary arrived in Scandinavia.

A photograph of the Lindisfarne Castle on the Holy Island, in England. Photo: Ian Ward / Unsplash

The Vikings raids on Christian societies

By the time of the first Viking raid, on the island of Lindisfarne, in 793 CE, Christianity had taken hold of many societies throughout Western Europe. Following the Western Roman Empire's fall in the late 4th century CE, Rome still exerted an oversized influence on many European polities as it was the center of power in the Catholic Church world. 

Despite the other Christian churches in "communion" with Catholicism (the great schism would not occur until 1054 CE), it was the Catholic strain of Christianity that held great sway in Europe.

Peoples in Viking societies had first been introduced to Christianity through Viking warriors raiding Christian communities in Northern France, Germany, and the British Isles. Whilst Rome was the undoubted center of the Catholic world, the Celtic Church in Ireland had for years sent out Christian missionaries to "heathen" cultures, and the Vikings encountered, in the British Isles, a culturally and economically rich and sophisticated religion. 

With raiding occurring all across the British Isles – which would, in time, become more permanent settlements (for example, the foundation of Dublin as a Viking trading post or the Danelaw region of northern England) - Vikings had everyday exposure to this new religion.

Flowing back to the Scandinavian homeland, after these raids, was a steady source of treasure and people. Not only were Christian gold and treasure ferried back, but raids also enslaved unlucky locals. These people, many from the British Isles, became the thralls (slaves) of Viking societies

However, as many were Christian, people in the Viking homelands saw firsthand exposure to the new Christian religion. A steady flow of enslaved "human capital," who were Christians, back to Scandinavia saw this new religion reach areas that a missionary never could.

The mission of Hamburg-Bremen

Beginning in the early 8th century, Christian missionaries began to travel north, from Germany, to Scandinavia. Yet they had limited success until Harald Klak, a petty king of Jutland, in Denmark, was forced into exile by his co-ruler, Horik I.

During this exile, Klak arrived, in 826 CE, in the court of Louis I, the Holy Roman Emperor. Louis was, at the time, co-Emperor with his more illustrious father, Charlemagne. In return for land and a title in the Frankish realms, Klak, his family, and supporters (numbering over 400) agreed to be baptized.

Upon his return to Denmark, Klak was joined by the Bishop of Hamburg-Bremen, Ansgar, to oversee the spread of Christianity and the proper conversion of the so-called "heathen masses." Yet when Klak was forced to flee again, Ansgar traveled further north to concentrate his efforts on Sweden. 

A Christian community was then established in Birka, Sweden, in 829 CE, and in 831 CE, founded the Archdiocese of Hamburg solely with the responsibility to spread Christianity into Scandinavia.

By the middle of the 9th century, the proselytizing mission of Ansgar began to have some success. The first Christian chapel built in Scandinavia was constructed in Hedeby in 854 CE, whilst a second was built in Ribe - an important trading town throughout the Viking Era. 

By 948 CE, Ribe's influence as a center of Viking trade and commerce at a crossroads between the Viking societies in Scandinavia and Christian societies further south and west saw it be promoted to an archdiocese.

Norway's geography presented the missionaries in Christian realms with a notable challenge. Photo: Unsplash

The tyranny of geography - early Christianity in Norway

The early spread of Christianity, in Norway, took a slightly different path from its Scandinavian neighbors. Aside from Vikings' exposure to Christianity overseas and the flow of Christian slaves back to Viking societies in Norway, Christianity's journey northward took time.

The geography of Norway presented the missionaries in Christian realms – especially from the Archdiocese of Hamburg-Bremen – with a huge challenge. The missionaries sent from the Frankish realms had to travel greater distances to reach the mountainous communities and petty kingdoms that dotted Norway in the early medieval period. 

The first recorded attempts of politically enforced conversion were under the reign of Håkon the Good in the mid-10th century. Having been raised in England, Håkon and his predecessor, Harald Greyhide, sent about spreading the Christian message with mixed results. Greyhide was also known for his destruction of pagan temples throughout Norway – which had the opposite effect and seemed to stiffen pagan spiritual resolve.

Yet it was under Olaf Tryggvason that the story of a Christian Norway really began. If we are to believe the epics, a visit to a seer on the British Isle of Scilly would change the course of Norwegian history. A promise for his future being told so long as he would be baptized as a Christian was kept when the seer's prediction about a mutiny on his return to Norway proved correct. 

Olaf kept his side of the bargain and was baptized in 995 CE, thus becoming Norway's first Christian king. He would, temporarily, stop raiding and destroying Christian communities throughout England and Ireland. After his return to Norway to seize the throne, Olaf I went about converting Norse settlements throughout his realms – including all of Norway, Greenland, Iceland, and the Shetland, Orkney, and Faroe islands.

By the beginning of the 11th century CE, Christianity had spread into Viking societies throughout Scandinavia thanks to the work of missionaries along with the steady flow of slaves from Christian societies throughout Northern Europe. 

By this time, Christianity and paganism often co-existed together throughout many communities. However, by the end of this century, Christianity's supremacy throughout Scandinavia, to the detriment of the Old Norse religion, as well as the beliefs of the Sami and Finns, would become evident.

For more on the early spread of Christianity into Viking societies, visit a BBC History Extra article here.

You can find our second article on the Christianization of Scandinavia here.

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