Barker received a degree in religion from Azusa Pacific University and was ordained to the ministry by the Standard Community Church, California, in 1975. He served as associate pastor at a Religious Society of Friends (Quaker) church, an Assembly of God, and an independent Charismatic church. To this day, he receives royalties from his popular children's Christian musicals, Mary Had a Little Lamb (1977) and His Fleece Was White as Snow (1978), both published by Manna Music.