Theodore Of Mopsuestia (350, Antioch — 428/429, Mopsuestia, Cilicia [now part of Turkey]), a pupil of Diodore of Tarsus (condemned by a local synod in Constantinople in 499 as a Nestorian) was at one point considered the greatest biblical interpreter of his time and the spiritual head of the exegetical School of Antioch.
Theodore, a theologian in the Antiochian “Word-man” Christological tradition (whose biblical exegesis and theological reflections became the standard in the churches in Persia after the 5th century), speaks in contradictory ways about Christ’s person and nature. When he asserts that “by nature God the Logos is one thing and that which is assumed is another” one might think he is speaking imprecisely about the distinction between the divine nature and the human nature. However, it becomes clear that he is speaking of the Logos who associates with the man Jesus, “in” him and “with” him – and in this way Theodore uses both adoptionist and Nestorian categories.
In earlier section of his “On the Incarnation” he sets the context by saying that God indwells in all creation, but in his chosen ones, by his ευδοκία, his good will, he indwells in a special way. He later makes clear that this is the way the Logos indwells in Jesus.
He often states that the Son is “one person.” But just as often he goes on to contradict such statements by saying that this Lord at a “later stage” had “the Logos of God working within him.” This is classical adoptionist language. The “Lord” was “urged on by the Logos” and had a “union with the Logos” – which he attained by showing himself worthy to receive God’s ευδοκία by his moral achievements, by his “cooperation with God the Logos.” (Book VII).
Theodore says that Jesus and the Logos are not two persons, but one, and there is no mixture in the natures, for they are distinct; he says that the personal union is not destroyed by the distinction of natures, as the person is complete and the nature of man is complete (Book VIII), which is correct. However, this is contradicted by his other statements.
Theodore clearly speaks of the Logos and Jesus as two distinct “ones,” the former uniting the latter to Himself. “God the Logos . . . united Jesus with himself” and this Jesus was “counted worthy of higher gifts that the rest of humanity” (Book VII). Again using adoptionist language, he is arguing that the man Jesus is virtuous and the Logos indwells him. When he considers whether Mary is the Θεοτόκος, he argues that She is man’s mother by the nature, and God’s mother by the relation (neither of which is true; She is not the mother of a nature, but of a Person with two natures, and that person is God the Son).
His views were eventually condemned in the 5th Ecumenical Council in 553.