Fourteenth century Norway is a perfect setting for an exploration of Christian beliefs about sin. The country was nominally converted to Christianity in the late tenth century by King Olaf I (Olaf Tryggvason), but many pagan beliefs and superstitions from the old Viking era persisted, especially among rural dwellers.
The new Christian religion promoted rules against pride, lying, killing, adultery, coveting material things, unchastity, and disobedience to parents. It taught that there is a high price to pay for breaking Church commandments. The willful young Kristin Lavransdatter repeatedly breaks many of these rules, then struggles to secure redemption for her sins. Her circle of close friends includes clergy and pious laypersons such as her father. She receives their spiritual counsel yet does not take their advice to heart. She goes through the motions of piety, saying her prayers and making a pilgrimage, but it is only in her last years that she achieves true spirituality.
In her early years, she is unable to repent for her sins, so they haunt her throughout her life. Her bitter thoughts make her hypercritical not only of herself but also of others. She cannot even forgive those close to her, especially her husband, Erlend, and eventually drives them away. The dying Kristin reevaluates her life in a scene in which she donates her wedding ring to the Church. After removing her ring, she sees imprinted on her skin the letter M, which stands for Saint Mary; the imprint shows the importance of divine love over earthly love. Kristin realizes that serving God’s will is foremost, that spiritual awakening is more important than momentary earthly happiness. Worldliness and self-absorption should be renounced for engagement with the divine. This insight mirrors the views of Sigrid Undset, who condemned twentieth century secularism and in 1924 converted to Catholicism (an unpopular move in Protestant Norway). Many Roman Catholic scholars view her book as one of the great Catholic novels of the twentieth century.