church of Sweden that, until 2000, was supported by the state; it changed from the Roman Catholic to the Lutheran faith during the 16th-century Protestant Reformation.

During the 9th century the Swedish people had gradually begun to accept Christianity. The first Christian missionary sent to Sweden was St. Ansgar (Ansgar, Saint) (801–865), a Benedictine monk and first archbishop of Hamburg. Subsequently, British and German missionaries worked among the Swedes, but the country did not become primarily Christian until the 12th century. In 1164 Uppsala was made the seat of an archbishopric, and the first Swedish archbishop was appointed.

The Reformation in Sweden did not involve a radical break with past church practices; the episcopal form of church government and the apostolic succession of the clergy were maintained. Gustav I Vasa, king of independent Sweden (1523–60) after the Scandinavian union of Sweden, Norway, and Denmark had broken up, wished to eliminate the extensive economic power of the Roman Catholic church in Sweden. He was aided in introducing the Reformation in Sweden by his chancellor, Laurentius Andreae, who had studied on the European continent and was aware of the new religious teachings, and by Olaus Petri (Petri, Olaus), the Reformer of Sweden, who had studied in Wittenberg, Ger., with Martin Luther (Luther, Martin) and Philipp Melanchthon (Melanchthon, Philipp). Ties with the Roman church were gradually weakened until 1527, when the king, with the approval of the Swedish Diet, confiscated the church's property, and the Church of Sweden became independent. Some of the clergy left Sweden rather than accept Lutheranism, but gradually the new religious teachings were accepted by the remaining clergy and the people. In 1544 the king and the Diet officially declared Sweden a Lutheran nation.

Petri was a teacher and preacher who served as pastor (1543–52) in the Storkyrkan (the Cathedral of St. Nicolas) in Stockholm, city councilman in Stockholm, and secretary (1527) and chancellor (1531) to the king. He served the Swedish Reformation in many ways. He prepared a Swedish New Testament (1526), a hymnbook (1526), a church manual (1529), and a Swedish liturgy (1531), and he wrote several religious works. The entire Bible was translated into Swedish by Olaus, his brother Laurentius Petri (Petri, Laurentius), and Laurentius Andreae; it was published in 1541.

Under the leadership of Laurentius Petri, first Lutheran archbishop of the Church of Sweden (1531–73), the church resisted attempts by Calvinists to influence its teachings and government. Laurentius prepared the “church order” of 1571, a book of rites and ceremonies that regulated the life of the church.

Subsequent attempts by Roman Catholics to regain power in Sweden were unsuccessful. Under King Gustav II Adolf, Lutheranism was no longer threatened, and Gustav's intervention in the Thirty Years' War has been credited with saving Protestantism in Germany.

Lutheran orthodoxy prevailed in Sweden during the 17th century. During the 18th and 19th centuries, however, Pietism, a movement that began in Germany and emphasized personal religious experience and reform, strongly influenced Lutheranism in Sweden. As a result, educational, social welfare, and mission activities were begun and carried on by the church. In the 20th century the church was active in the ecumenical movement. Archbishop Nathan Söderblom (Söderblom, Nathan) was an ecumenical leader whose work was eventually influential in the formation in 1948 of the World Council of Churches. In 1952 a law was passed that allowed a Swedish citizen to withdraw formally from the state church and not be a member of any church.

Although different religions were accepted in Sweden after the Edict of Toleration of 1781, the Church of Sweden continued as the state church, with the king as its highest authority, into the late 20th century. However, beginning in the mid-1990s, the Swedish Parliament approved a series of reforms aimed at promoting religious freedom, and in January 2000 the church ceased being supported by the state. In addition, Lutheranism stopped being the country's official religion.

The country is divided into 13 dioceses, each headed by a bishop. The archbishop of Uppsala is bishop in his diocese and presiding bishop of the Church of Sweden. Bishops are elected by priests of the diocese and by lay delegates. The Church Assembly is the decision-making body. It has 251 elected members and meets two times a year.