After serving in the military as a trombonist in the Band of the King's Guard, Alfsen entered the Conservatory of Music in Oslo.
His albums with Reflex were important contributions to the repertoire of Christian choirs and music groups throughout Scandinavia.
The song became a Christian music hit, and was covered by a number of European choirs and the American gospel group The Kurt Carr Singers, for their album Serious About It.
In the mid-nineties, Alfsen was the musical director for a popular Norwegian TV series presenting well-known traditional Christian songs and church hymns.
In 2021, he was commissioned to write a choir cantata for the celebration of the 250th anniversary of Hans Nielsen Hauge, the Norwegian preacher and politician.