The belief that Jesus was an ordinary human who became the Son of God at his baptism. Early Christians rejected Adoptionism because it contradicts New Testament teaching; according to John 1:1, Jesus ("the Word") was divine from "the beginning." John the Baptist (a cousin of Jesus who announced the Messiah's coming) and Jesus himself testified that he existed before his earthly birth. (cf. John 1:15; 8:58). See also Christology.