Its story
'Adoptionism' names two different phenomena, separated by more than five centuries, that should not be confused. The first, also called 'dynamic monarchianism', appeared in the late 2nd century: to protect the oneness of God (the 'monarchy'), it held that Jesus was a man—virgin-born, according to some—on whom God's power (dynamis) descended at his baptism, and who because of his virtue was adopted as Son. Theodotus the Tanner, from Byzantium, taught this in Rome and was excommunicated by Pope Victor (c. 190); Theodotus the Banker and Artemon followed him.
Its best-known representative was Paul of Samosata, bishop of Antioch, who reportedly taught that the Logos dwelt in the man Jesus as in a temple, without being a person distinct from the Father. A synod at Antioch deposed him in 268, although he kept his see until Emperor Aurelian had him removed (c. 272). According to later sources that synod rejected the term homoousios in the sense Paul used it, a fact that later complicated the debates over Nicaea. He is known mainly through Eusebius and fragments preserved by opponents.
The second phenomenon is the Spanish Adoptionism of the late 8th century. Elipandus, archbishop of Toledo in Muslim-ruled Spain, and Felix, bishop of Urgell, held that Christ is Son of God by nature in his divinity but 'adoptive son' in his humanity, drawing on expressions from the old Hispanic liturgy. Their aim was not to deny Christ's divinity but to distinguish his two natures; their critics—Beatus of Liébana, Alcuin of York, Paulinus of Aquileia, Pope Hadrian I—held that the formula divided Christ into two sons, in Nestorian fashion.
Charlemagne convened synods at Regensburg (792), Frankfurt (794) and Aachen (799), and Pope Leo III condemned the teaching at Rome (798). Felix recanted and spent his last years under supervision in Lyon (he died in 818); Elipandus, beyond Frankish reach, did not recant and died around 805. Some historians also see in the controversy a tension between the Hispanic Church and rising Carolingian authority. In modern theology 'adoptionist' is sometimes used for Christologies that see Jesus only as a man exalted by God.