Norwegian religious expression is largely private; whereas most individuals state that religion is important to them, this is not generally expressed through active religious participation in organized communities. While roughly 80% of the population belong to the Church of Norway, only 10% attend church services or other Christianity-related meetings more than once a month.
Some 5.9% of the population are members of other religious communities, while 6.2% do not belong to any religious community at all. The largest religious and life-stance communities outside the Church of Norway are the Humanist Movement, represented by the Norwegian Humanist Association (63 000), Islam (60 000), the Pentecostal Movement (45 000), the Roman Catholic Church (40 000 or more), the Evangelical-Lutheran free church (20 000), Methodists (13 000) and several lesser free churches.
The conversion of Norway to Christianity started in around 1000 and was a result of contact with Christian Europe through a combination of trade ties and Viking raids. Missionary activities conducted by the Anglo-Saxon church as well as from Germany and Denmark also helped Christianity to gain prominence over the gods of traditional Norse mythology and Sámi nature worship.
Christian Norway belonged to the Roman Catholic Church until the Reformation of 1537. A ban on lay preaching was lifted in 1842, giving rise to several free church movements and a strong lay organization within the Church of Norway. As a result, Norwegian church society became closely associated with a conservative Christian interpretation and an active missionary movement.