Technically, the term "adoptionism" refers to a Christian heresy that was developed in the eighth century by a Spanish bishop called Elipandus of Toledo. Elipandus maintained that the divine Jesus was God's son by "nature," while in his human life, Jesus was "adopted" as God's son. This view, which seems to be related to Nestorianism, was condemned at the Council of Frankfurt in 794, though it resurfaced from time to time throughout the Middle Ages.

In a broader sense, "adoptionism" is any belief that Jesus was the adopted son of God, as opposed to a preexistent being who shares his nature with God. According to this view, Jesus was a mere human being for at least the first thirty years of his life. As early as the second century, one Theodotus the Byzantine (not to be confused with any of at least a dozen other early Christians named Theodotus) was arguing that Jesus was not singled out for God's favour until he had proven himself at his baptism, which is when he received his miraculous powers. After his crucifixion, according to Theodotus, Jesus was adopted fully into the Godhead. Interestingly, Theodotus agreed with the view that Jesus was born of a virgin.

An adoptionist perspective seems to find support in certain Old Testament passages that are frequently cited in early Christian literature. In Psalm 2:7, God addresses an unnamed king: "You are my son; today I have begotten you." In 2 Samuel 7:14, God promises that he will call the future Messiah his son, but the placement of the verse after the description of the future king's palace and throne suggests that God's declaration of sonship will not happen until the Messiah has already reached adulthood.

The fact that Mark, the earliest gospel, sees no need to describe Jesus' birth -- or, for that matter, any part of Jesus' life before the beginning of his ministry -- implies that at least one evangelist had no interest in making a case for Jesus' eternal, unbegotten nature. Arguably this is true of the other synoptic gospels as well, though it is not the case for John.

Since all this Christology business can be awfully confusing, allow me to make a couple of closing observations.

• All adoptionists are subordinationist, which is to say that they believe Christ is not coequal with the father. All forms of subordinationism are technically heresies. Small-o orthodox Christianity holds that Christ and God are coequal and coeternal.
• Early adoptionists are sometimes called dynamic monarchians, because they tried to preserve God's "single rulership" (monarchia) at the expense of Jesus' divinity. Monarchianism is also a heresy.
• Arians are not adoptionists, but they are subordinationist. Arius believed that Jesus was the eldest and brightest of all creatures -- even older than the angels, and therefore not a mere man -- but that he was nevertheless a creation of God. Arianism, as it happens, is a heresy too. Orthodox Christianity holds that Jesus is uncreated and unbegotten (or, to be more precise, eternally begotten).

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