Religion in Norway was pagan until about 1000 AD, when Christianity finally took hold. Norwegian cosmology--native ideas about the origin and structure of the universe, and the place of humans in it--reflected the most basic elements of a harsh arctic environment, as well as the brutal combat common among warring North Germanic tribes. The Prose Edda, written around 1220 AD by Icelandic historian Snorri Sturluson, described this ancient creation belief.
In the earliest time, nothing existed except a yawning chasm. Icy mists swirled to the north, fire and blinding light stretched to the south, and a hard frost formed in the middle. The frost was poisonous because an evil influence was already at work. This frost produced Ymir the Frost Giant, a mighty and evil creature in the likeness of man.
A giant cow was also formed from the hard-frost region. Her milk fed Ymir and his children. One day the cow licked a block of ice and uncovered a giant, Buri. From Buri sprang a young Odin and his two brothers. Odin became chief among the heroic gods called the Aesir, who mirrored the Old Norse culture of a warrior aristocracy.
The three young gods and the frost giant could not live together in peace, and when the gods were old enough, they killed Ymir and dismembered him, forging the earth and sky from different parts of his body. Then Odin and his brothers carved out the first man and woman from two trees, and breathed life into them.
This creation myth was widely shared among different clans, and was symbolic of a culture where the martial virtues of strength, courage, and resourcefulness were admired. Conflict was regarded as natural, if not inevitable, and was typically resolved by violence. Warriors usually worshiped Odin, even though he was known for arbitrarily sponsoring and then abandoning mortal heroes.