Jesus, a human being, was chosen by God to be elevated to divine sonship, either at His baptism or after the resurrection.
A belief, universally held within the earliest Christian movement, and still active in the 2nd and 3rd century CE, that Jesus was a normal human being, a prophet, who was born as any other human, and is not a deity. God later gave him supernatural powers at his baptism when God chose Jesus as his " adopted" son. Adoptionism was declared a heresy b a number of early church councils.
Technically, an eighth century doctrine originating with Spanish theologians who taught that the man Jesus was adopted into the Sonship by an act of God. In general, any belief that Jesus was a man who was elevated to divinity at some point in his life.