When did Christianity begin spreading to Finland through Sweden?

The spread of Christianity to Finland through Sweden began in the 12th century. While Christianity was known in the region as early as the 11th century, organized efforts to establish the church intensified during the 12th century under the influence of Sweden.1234

Tradition holds that the first Swedish crusade was undertaken around 1157 by King Erik, who was accompanied by the English bishop Saint Henry. Henry remained in the region to organize church affairs and eventually became Finland’s patron saint. Throughout the 12th and 13th centuries, Swedish expeditions took on the character of crusades as Sweden competed with other powers for influence in the region. By the 13th century, Sweden had established a firm role in the Christianization of Finland, a process that continued until the country transitioned to the Lutheran faith during the Protestant Reformation in the 16th century.1243