Only 48 percent of the church members polled by Respons Analyse said they considered themselves to be Christian.
This compared to 33 percent, who said they were atheist, 14 percent who said they believed only in a “a creator”, and one percent who said they were active followers of another faith.
Helga Haugland Byfuglien, Praeses of the Norwegian Bishops' Conference, said that the result was not surprising.
“We recognise that we as a church are challenged by new trends at this time,” she said.
“Many feel that being a Christian requires a special devotion with a requirement for dedicated and active participation. But there are many nuances when it comes to faith, and for many the church means a lot as a bearer of tradition and culture.”
Andres Vassenden, a sociologist of religion at the University of Stavanger, said that Norwegians' attitude to religion was “complex”.
“People can define themselves as an agnostic, but still experience their membership in the church as undramatic,” he said.
Respons Analys surveyed 706 church members for the poll.