Part of the reason that Norway has such a high percentage of people in the Church of Norway is because up until recently (1990's) almost everyone born in Norway was automatically enrolled in the church regardless of denomination.
Please remember that christianity in Scandinavian countries are very, very different than US christians as well. The ones in the US are merely obnoxious in many cases and think everybody should follow their rules. In Norway that behavior is not tolerated from anyone. A lot of your TV preachers and outspoken "anti" types would be in jail for hate speech. It's happened before to preachers who said that gays and pagans/heathens should be put to death as it states in the bible.
Also please bear in mind that in Scandinavian countries a large percentage of those that believe in a deity will point to our own, traditional deities, and not the christian deity, regardless of which church they were enrolled in at birth.
So while Norway may not be an atheist country, it's a christian country in name only. Unless you count the fact that we actually care for people after they're born and provide things like higher education and health care for everyone. Then we're more christian than most christians even if we're not christian. We're not selfish in other words. The health of the tribe *is* dependent on the health of the entire community, you know.
Edit: John, like I said - we didn't have a choice if we wanted to be "christians" or not. We are enrolled at birth. Everyone in my family is a member of the Church of Norway yet not a single one of us is a christian. The numbers in that regard are very misleading. To a lot of us the "higher power" would be Oðin or one of his cohorts, not a foreign, desert deity. That would simply make no sense - and we ARE a very practical lot, you know.
Norwegian expat in the US