Adoptionism is a heresy asserting that God adopted Jesus as His Son because Jesus was living a sinless life. This false belief is also called dynamic monarchianism and came on the scene early; the church declared adoptionism to be heretical in the second century. All men are born into sin (Romans 5:12–14); had Jesus been a mere man, He would not have been sinless. Jesus Christ was not adopted by God; He existed from before the beginning of creation and is part of the triune Godhead. Jesus is "begotten" (John 3:16, KJV), not adopted.
What does Adoptionism teach? Is it biblical?
Of Jesus, Colossians 1:16–17 says, "For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together."
John, in the first chapter of his Gospel, describes Jesus as the Word of God becoming flesh, and then coming to Earth from God (John 1:1; 14). John says Jesus is the "only Son from the Father." Jesus existed before coming to Earth and has always had the same divinity as God the Father.
Those who adhere to adoptionism claim Jesus was just a man who lived perfectly. We know from Scripture that Jesus was indeed sinless (2 Corinthians 5:20–21). However, He was able to live sinless because He was divine (John 1:1, 14), not because He had a certain ability or willpower or discipline to keep the law. Keeping the law (an impossibility) cannot justify a person, even if it was possible (Romans 3:19–20).
John the Baptist declared Jesus as the "Lamb of God, who takes away the sin of the world!" (John 1:29). If Jesus was a good guy who God noticed, John would not be able to declare His coming sacrifice on behalf of those who believed. Other, older prophesies declared that the Savior would be born of a virgin (Isaiah 7:14), die by crucifixion (Psalm 22), and be an atoning sacrifice (Isaiah 53:5, 12). None of those would be realized if Jesus was a good man whom God chose sometime later in His earthy life.
Adoption is an important theological theme in the Bible, but it has to do with Christians becoming a part of God's family through Jesus (Ephesians 1:5). It is we who are adopted through Christ, not Jesus who was adopted.
Who is Jesus Christ?
Is the doctrine of eternal sonship biblical? What is meant by eternal sonship?
What does 'only begotten Son' mean? How is Jesus God's only begotten Son?
How is Jesus the first-born over Creation? What does it mean for Jesus to be the first-born?
What is the theological concept of the hypostatic union?
Truth about False Beliefs