Iceland Adopts Christianity by Law

Estimated date

At the Althing the pagan lawspeaker Thorgeir, asked to settle the dispute between Christians and heathens, rules that all Icelanders shall be baptized and live under one law, with a few old customs allowed for a time.

The account followed here is that of the priest Ari Thorgilsson, written some 120 years later from what he had been told by Teitr, whose grandfather Gizurr the White was one of the Christian leaders (Ari, Íslendingabók 1; 9). According to Ari, King Olaf Tryggvason of Norway sent a priest named Thangbrand to Iceland. He baptized several chieftains, among them Hallr of Síða, Hjalti Skeggjason and Gizurr the White, but most people rejected the new faith, and after killing two or three men who had mocked him he went back and told the king that Iceland would not be converted. Olaf threatened to maim or kill the Icelanders then in Norway. Gizurr and Hjalti obtained their release by promising to try again (Ari, Íslendingabók 7).

The next summer the two men sailed home and rode to the Althing, the general assembly held at Thingvellir. Hjalti had been outlawed there the year before for a verse mocking the goddess Freyja. The heathens gathered in arms, and it came close to a battle. When Gizurr and Hjalti had spoken at the Law-Rock, Christians and heathens each declared that they would no longer live under the same law as the other (Ari, Íslendingabók 7).

The Christians asked Hallr to proclaim a law for them. He arranged instead that the lawspeaker, Thorgeir Thorkelsson, who was still a heathen, should do it. Thorgeir lay down under his cloak for a day and a night without speaking. The next morning he called the people to the Law-Rock and told them that if they did not all keep one law, fighting would follow and the land would be laid waste; a divided law, he said, meant the end of peace. Both sides agreed to accept what he would proclaim. He then declared that all should be Christians and that those not yet baptized should receive baptism. The old law was to stand on the exposure of infants and the eating of horseflesh, and people might sacrifice in secret, though they would be outlawed if witnesses could be brought. A few years later, Ari adds, these exceptions were done away with (Ari, Íslendingabók 7).

In Ari’s telling Iceland became Christian by a decision of its own assembly, taken to keep the peace, though under pressure from the Norwegian king. Olaf, he notes, fell in battle the same summer (Ari, Íslendingabók 7).

How this is dated

Estimated date. A scholarly estimate from primary evidence, with a margin of years.

Ari sets the decision in the summer in which King Olaf Tryggvason fell, 130 years after the killing of King Edmund and 1000 years after the birth of Christ by the common reckoning (Ari, Íslendingabók 7). He wrote between 1122 and 1133, a span the translator fixes from the two bishops named in his prologue, about 120 years after the event, and from the account of his foster-father Teitr (Ari, Íslendingabók 1; 9).

The translator, Siân Grønlie, notes on this passage that Ólafía Einarsdóttir, Studier i kronologisk metode i tidlig islandsk historieskrivning (Bibliotheca Historica Lundensis 13, 1964), argued for 999: if Ari began his year on 1 September, Olaf’s death in early September 999 would fall in his year 1000, and the assembly of that summer would likewise belong to what is now counted as 999. The timeline shows both years.

Primary sources

Every citation on this page was independently checked against its source on 3 October 2026.

In context

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  1. AD 829 to AD 831, estimated date

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