According to Snorri Sturluson (a 12th and 13th century Icelandic historian), he was baptized in 998 in Norway, but more probably about 1010 in Rouen, France, by [[Archbishop]] Robert. In his early youth he went as a viking to England, where he took part in many battles and became earnestly interested in Christianity. After many difficulties he was elected King of Norway, and made it his object to extirpate heathenism and make the Christian religion the basis of his kingdom.
He is the great Norwegian legislator for the Church, and like his predecessor Olaf Tryggvason, made frequent severe attacks on the old faith and customs, demolishing the temples and building Christian churches in their place. He brought many [[bishop]]s and [[priest]]s from England, as King Canute IV later did to Denmark. Some few are known by name (Grimkel, Sigfrid, Rudolf, Bernhard). He seems on the whole to have taken the Anglo-Saxon conditions as a model for the ecclesiastical organization of his kingdom.
But at last the exasperation against him got so strong that the mighty clans rose in rebellion against him and applied to King Canute II of Denmark and England for help. This was willingly given, whereupon Olaf was expelled and Canute elected King of Norway. Olaf fled to Kievan Rus, and during the voyage he stayed some time in Sweden in the province of Nerike where, according to local legend, he baptized many locals.
== St. Olaf's cultus==
Many miraculous occurrences are related in connection with his death and his disinterment a year later, after belief in his sanctity had spread widely. His friends, Bishop Grimkel and Earl Einar Tambeskjelver, laid the corpse in a coffin and set it on the high-altar in the church of St. Clement in Nidaros (now Trondheim). Olaf has since been held as a [[saint]], not only by the people of Norway, whose [[patron saint]] he is, but also by Rome. Orthodox Christians also venerate him as one of the ancient western saints of the Church before the [[Great Schism]].
In 1075, his incorrupt body was enshrined in what became the cathedral of Nidaros (Trondheim), which replaced the chapel, and became a site of pilgrimage. During the Protestant Reformation his body was removed and reburied. His cultus was aided by the unpopular rule of Swein, Canute's son; Canute's death in 1035 resulted in the flight of many Danes from Norway and the accession of Olaf's son Magnus. Thereafter his cultus spread rapidly. Adam of Bremen (c. 1070) wrote that his feast was celebrated throughout Scandinavia.