 Schjelderup was imprisoned in Grini concentration camp by the Nazi occupiers of Norway in 1942.Shortly after the war he was ordained, worked one year as a chaplain in Oslo, and was appointed by King Haakon VII of Norway and the Gerhardsen Cabinet as Bishop of Hamar in 1947.In 1953–1954, he took part in the notorious public debate on the existence of Hell, where he strongly criticized a radio-transmitted speech by Professor of Theology Ole Hallesby, in which Hallesby had warned the population that they might go to Hell.