 Knudsen was also noted as a prolific hymn poet, and two of his hymns has later been included in the Norwegian hymn book, as well as the hymn books of other churches.Knudsen was born on 24 September 1937 in Vennesla, Vest-Agder, to priest Rolf Godwin Knudsen (1907–56) and Nina Lydersen (1913–95).He grew up in Langesund where his father was the local parish priest.