Religion in Iceland has been predominantly Christianity since its adoption as the state religion by the Althing under the influence of Olaf Tryggvason, the king of Norway, in 999/1000 CE. Until then, in the 9th and 10th centuries, the prevailing religion among the early Icelanders — who were mostly Norwegian settlers fleeing Harald Fairhair's monarchical centralisation in 872–930, with some Swedes and Norse British settlers — was the northern Germanic religion, which persisted for centuries even after the official Christianisation of the state.
Early Icelandic churches maintained the style of Heathen hofs, often featuring dragon finials on the roof, such as in the case of the old church of Thingvellir (the current one goes back to 1859, while the steeple was rebuilt in 1907), built by initiative of King Olaf of Norway, who provided timber and the bell, to mark the official Christianisation of Iceland in the year 1000.