Thor versus the Volcano: The Christianization of Iceland

Trying to understand the Vikings takes some patience and careful research. They built homes of wood and turf, and their clothes were mostly wool and linen, so much of the physical evidence of their travels and lifestyle has been ravaged by natural processes. Viking societies depended heavily on oral communication, and many of the texts we have today were written down a century or more after the Viking Age. Determining how the information may have changed over that time is tricky business, and we can only guess how many stories were completely lost over the years. One story that has survived is the Christianization of Iceland. But did the Icelanders turn to Christianity out of fear of volcanic eruptions, as some researchers have suggested?

Some Background about Iceland

The human history of Iceland is somewhat peculiar. Prior to the Viking age, humans did not inhabit the island, but there is archaeological evidence that the Norse knew of the island by the start of the ninth century. The sagas indicate that Iceland was settled permanently about 70 years later by Norse families that refused to bow to Harald Hårfagre, the first king of Norway.1  These settlers developed a decentralized and rather democratic system of government that employed a complex system of laws and legal assemblies to resolve disputes.2

It seems that those early settlers were quite intent on maintaining their existing identities and social roles. The legal system they designed effectively prevented any one person from taking power for themselves (no more kings!) and granted the free people of Iceland significant individual autonomy. The downside, however, was that they had no formal police or military to enforce these laws, so according to the sagas, people regularly took matters into their own hands.

The preservation of the sagas and myths also demonstrate the relative strength of the Icelanders’ desire to retain their social identity through cultural, historical,  and genealogical knowledge. The sagas in particular were detailed stories of the Icelanders,  including the names and family relationships of the early settlers. Again, the Vikings did not write down their stories but passed them on entirely by spoken word, stories memorized by generation after generation and committed to writing a century or more after the pagan traditions had been largely been abandoned.

One thousand years later, Icelandic culture is still heavily influenced by the ways of those early settlers. The sagas are generally well-known by the Icelandic people, for whom storytelling still occupies a special place in their culture. One in every ten Icelanders will publish a book in their lifetime.

Even naming your baby can get a bit complicated. There are approved baby names for males and females, and you need permission to choose a name that has not already been approved. Fortunately for creative parents, most names get rubber-stamped as long as the spelling conforms to Icelandic conventions. Additionally, babies are not officially named right away. The parents wait several months before baptizing and formally naming their child, a practice that reflects the country’s Viking Age roots, when sickly infants were sometimes exposed and left to die. Performing a naming ritual signified the child’s acceptance into the family. (You can learn more about Viking naming ceremonies here.)

Monotheism v. Polytheism

Old traditions die hard, and faith-based traditions are no exception. Answering questions concerning the religious conversion of the Icelanders, and indeed of all medieval Scandinavians, is perhaps not as straightforward as it might at first seem.

One key point to remember is that polytheistic religions often produce a rather different mindset than what may be familiar to many in the modern Western world, where monotheistic faiths loom large. Those who worship a pantheon of gods look to each god for support and protection in different areas of life, and it is not a snub to seek the assistance of different gods at different times. For example, in Greek and Roman mythology, the gods all had their favourite humans, and heroes sought the protection of the gods who favoured them—especially when another god was trying to kill them. Roman families also worshipped household gods. In the case of the Vikings, the gods were divided into two overarching groups: the Aesir, the gods of war and victory (Odin, Thor, Tyr, etc.) and the Vanir, the gods of fertility and prosperity (namely Freyja, Freyr, and Njord).

As a side effect, religious tolerance may be higher among the adherents of polytheistic faiths. If you already believe in a pantheon of gods, being introduced to yet more deities is not going to shake your faith—what’s a few more gods? The presence of multiple faiths in society would not be seen as a threat, and may even be an economic blessing. Moulds cut to produce both Thor’s hammer pendants and Christian crosses have been found in various locations, and a cross-like Thor’s hammer pendant was discovered in Iceland.

Replica of an Icelandic Thor’s hammer (Mjöllnir) pendant with wolf’s head.

Additionally, polytheism tends to dampen the need to create new converts, because if your gods aren’t the only gods, the idea of a “true god” probably doesn’t even occur to you. One god may be more powerful than another, but to polytheists, social hierarchies among the gods may be as natural as human hierarchies. If you want to worship a lesser god, that’s your problem. Conversely, if you believe you have found gods more powerful  than those you already worship, then it makes sense to follow those gods.

Christianity in Northern Europe

Iceland was a mix of Vikings and Christians up until the lawspeaker decreed it a Christian land in or around 1000 CE, but there is evidence that the pagan converts were permitted to retain some of their traditions, at least for a time. But if the Vikings were so attached to their pagan way of life, why give it up?

First of all, the evidence suggests that throughout Scandinavia the Vikings’ conversion to Christianity was slow. Grave finds indicate that cross pendants appear in the ninth century and Thor’s hammer pendants were worn into the twelfth century; in some places, laws against pagan traditions were still being written in the fourteenth century.3  Clearly, the old gods had not simply been brushed aside and forgotten.

Meanwhile, competing social and economic forces were at play. Viking travels to mainland Europe put them into contact with Christian and Muslim societies, and envoys occasionally accompanied them back to Scandinavia (see Ibn Fadlan and al-Ghazal). As individual Scandinavians began converting to Christianity and Viking communities began expanding into kingdoms, political pressures may have played an increasing role in encouraging Scandinavian leaders to convert to encourage friendly relationships with other European kingdoms.

These transitions, were far from smooth, however. Danish king Harald “Bluetooth” Gormsson claimed to have converted his people to Christianity as a way to discourage attacks from not-so-friendly German forces. Harald was later deposed by his own son, which appears to be in part a rejection of the new religion and in part a response to the heavy labour and costs associated with the building of numerous fortresses and other defensive structures. Norway endured civil wars that were partly inspired by religious conscience, and in Sweden, no formal Christian governance was established until sometime in the twelfth century.4

Volcanoes, You Say?

Clearly, there were a lot of factors involved in the shift from Viking paganism to Christianity in Scandinavia, volcanic activity notwithstanding. Were the Icelanders influenced by geological events, as some researchers believe? Perhaps, but I’m not convinced. Overall, I find the connections being drawn between volcanic activity and religious stresses in Iceland to be tenuous at best.

Volcanoes in the Poetic Edda

While I have no doubt that the volcanic eruption described in the eddic poem “The Seeress’ Prophesy” matches the devastating effects of the Eldgjá  eruption in 939-940 CE, the relationship between that eruption and Iceland’s conversion to Christianity sixty years later isn’t exactly clear. Given the evidence that the researchers cite, the Eldgjá flood basalt eruption affected environmental conditions throughout Europe and Asia. Nonetheless, the Icelanders did not leave the island or seek to convert at that time, despite the hardships that they must have faced. In fact, several generations of pagans kept the old faith before the lawspeaker, Thorgeirr (a pagan), declared that Icelanders would adhere to Christian practices. It’s hard to imagine that the descendants of those who lived through the eruption would be so heavily influenced by an event that they never experienced. If anything, it’s likely that the survival of their parents and grandparents would have strengthened their faith in Odin and his kin, and the incorporation of the eruption into the existing mythology supports that position.

Additionally, I’m sceptical of the idea that The Seeress’ Prophesy actually foretells the Vikings’ conversion to Christianity. There are, in fact, two versions of this poem—one that properly belongs in the Poetic Edda (also known as the Codex Regius) and another that appears in Hauksbók, which appears to be a later text.5 Only this second poem contains any reference to “the mighty one,” which could just as easily be a reference to the return of Odin’s favoured son, Baldr, after Ragnarök.6 I also suspect that if the Hauksbók version of the poem was recorded at a later date, the further entrenchment of Christianity may have encouraged the writer to put a gentle “spin” on the poem, although that is speculation on my part.

Volcanoes in the Sagas

Kristni Saga  describes the events leading directly to the conversion of Iceland, including  a reference to a volcanic eruption that occurs during or just before the assembly in question. But while the event is contemporary with the conversion, I find its relationship to the lawspeaker’s decision just as weak.

In the saga, a man at the assembly describes an eruption that was about to engulf someone’s home, and the pagans present at the Law Rock say it is no surprise that the gods are enraged. A Christian man rebuts, asking “What were the gods enraged by when the lava we are standing on here and now was burning?”7,8

The argument ends here, but it doesn’t really address the issue at hand. If the men assembled had believed that the old gods were punishing or threatening them in some way, that likely would have discouraged them from converting; if the eruption was not believed to have been caused by angry gods, then it should have had no effect either way. However, the saga’s clear description of the lawspeaker’s decision demonstrates that the purpose of making Christianity the official religion was to prevent social upheaval, not appease anyone’s displeased deities.

Immediately following the argument over the volcano, the pagans and Christians both declared that they wished to live under separate laws, and each faction vowed to make human sacrifices to their respective gods. The next day, Thorgeirr announced his decision that all Icelanders should be baptized and live under a common law to keep the peace, although some concessions would be made to each side.9 It seems the men to be sacrificed were spared and the rule of law was preserved.

If we are to put stock in the historical accuracy of this saga, then we should assume that the lawspeaker’s concerns, described at length, were in fact the most likely reasons for conversion. The role (if any) played by volcanic activity appears to be small and inconsequential, and these eruptions could just as easily have been taken as a sign that the pagans should convert as a sign that they shouldn’t.


Given the immediate and dire consequences of a divided people and the tangential relationship between the volcanic events of the tenth century and the religious concerns of the Icelanders, I do not believe that these eruptions significantly influenced the final decision either way. This is not to say that the eruptions did not or could not have affected the beliefs of individual Icelanders, but rather that this effect (if it existed) was probably very small.

  1. Harald Fairhair, the king for whom the Norwegian ship Draken Harald Hårfagre was named.
  2. Thorsson, Örnólfur, ed. and Bernard Scudder, assistant ed. The Sagas of Icelanders. Penguin Books, Toronto [2001], pp 735–739. See also the introduction in Grágás I:  Bessason, Haraldur and Robert J. Glendinning, ed. Laws of early Iceland, Grágás I. transl. Dennis, Andrew, Peter Foote, and Richard Perkins. The University of Manitoba Press, Manitoba [2006], pp. 1–13.
  3. Williams, Gareth, Peter Pentz, and Matthias Wemhoff, eds. Vikings: Life and Legend. Cornell University Press, Ithaca, New York [2014], pp. 183–186. 
  4. Williams, Gareth, Peter Pentz, and Matthias Wemhoff, eds. Vikings: Life and Legend. Cornell University Press, Ithaca, New York [2014], p. 184. 
  5. Larrington, Carolyne, transl. The Poetic Edda. Oxford University Press, New York [2014], p. 10 [x] of the introduction.
  6. Larrington, Carolyne, transl. The Poetic Edda. Oxford University Press, New York [2014], p. 281 stanza 59 and p 321 note 59.
  7. Faulkes, Anthony, and Alison Finlay, eds. Íslendingabók—Kristni Saga. trans. Siân Grønlie. Viking Society For Northern Research, University College, London [2006], p. 48-49.
  8. Although it is not entirely clear where the Law Rock (Lögberg) was located, Thingvellir National Park has seen its share of volcanic activity in the past. 
  9. Faulkes, Anthony, and Alison Finlay, eds. Íslendingabók—Kristni Saga. trans. Siân Grønlie. Viking Society For Northern Research, University College, London [2006], p. 49-50.

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