Christianity was the religion of virtually all of the Swedish population from the 12^th to the early 20^thcentury, though it rapidly declined throughout the late 20^th century. Initially part of the Catholic Church, the Sweden switched to Lutheranism in the 1530s as part of the Protestant Reformation.

In order to curb Pietism, several royal decrees and parliament acts were issued in the 18^th century, forbidding Swedish citizens to practice any religion besides mandatory Lutheran Sunday mass and daily family devotions. Without the presence of a Lutheran clergyman, public religious gatherings were forbidden. It remained illegal until 1860 for Swedes to convert to another religion.

In 1860, it became legal to leave the Church of Sweden (Lutheranism) for the purpose of becoming a member of another officially recognized religious demonization. It was not until 1951 that it became legal to leave the Church without providing any reason.