either of two Christian heresies: one developed in the 2nd and 3rd centuries and is also known as Dynamic Monarchianism (see Monarchianism); the other began in the 8th century in Spain and was concerned with the teaching of Elipandus, archbishop of Toledo. Wishing to distinguish in Christ the operations of each of his natures, human and divine, Elipandus referred to Christ in his humanity as “adopted son” in contradistinction to Christ in his divinity, who is the Son of God by nature. The son of Mary, assumed by the Word, thus was not the Son of God by nature but only by adoption.

Opposition to this view of Christ was expressed, which led Pope Adrian I to intervene and condemn the teaching. Elipandus gained the support of Felix, bishop of Urgel, who eventually engaged in a literary duel with Alcuin of York over the doctrine.

In 798 Pope Leo III (Leo III, Saint) held a council in Rome that condemned the “Adoptionism” of Felix and anathematized him. Felix was forced to recant in 799 and was placed under surveillance. Elipandus remained unrepentant, however, and continued as archbishop of Toledo, but the Adoptionist view was almost universally abandoned after his death. It was temporarily revived in the 12th century in the teachings of Peter Abelard and his followers.