Adoptionism: heresy that Jesus was a pre-existing and non-divine human being, who received divine favour or status, for instance at baptism.
Anhypostasis / Enhypostasis: that there was no human Jesus “before” or other than assumption of humanity by the Son (anhypostasis); that the Person of the human being Jesus is the Person of the Son (enhypostasis).
Apollinarianism: heresy associated with Apollinaris of Laodicea (died 390), who proposed to combine human and divine natures of Christ by Word taking the place of the human soul.
Arianism: heresy of Arius (2nd-3rd century) — that Christ is a created demigod and not “of one substance with the Father”.
Communicatio idiomatum: Latin “communication of properties” — teaching that while human and divine natures of Christ have proper properties (e.g. weakness and omnipotence, respectively), these can be said, in secondary sense, of the other nature (e.g. that God suffered in Christ’s human nature). See homoousios.
Consubstantial: see homoousios.
Homoousios: Greek “of the same substance” — confession that the Second Person of Trinity (and by later extension, the third) is of equal divinity, majesty, and eternity with the Father.
Hypostatic union: teaching that union of the human and divine natures in Christ is by belonging to the one and same Person (Greek hypostasis).
Kenosis: proposal that the Eternal Son limited himself in becoming incarnate, from the Greek ekénosen — “he emptied himself” (Philippians. 2.7). That Pauline phrase, however, was more often interpreted by the early Church as humiliation of Incarnate Word (e.g. crucifixion) rather than as circumscription of divinity at Incarnation, since “in him the whole fullness of deity dwells bodily” (Colossians 2.9).
Logos: Greek “word” or “reason” — term for the Second Person of the Trinity, following John 1.
Monophysitism/Eutychianism: heresy, reacting to Nestorianism, stressing unity of divinity and humanity in Christ to the extent of having only one nature, either divine or hybridised (positions explored by Eutyches of Constantinople, c.380-456), from the Greek monos (single) and physis (nature). Condemned by the Council of Chalcedon (AD 451). See also miaphysitism.
Miaphysitism: Christological position of Oriental Orthodox Churches, from the Greek mia (one) and physis (nature), which do not follow the definition of the Council of Chalcedon (two natures in one Person), for fear of Nestorianism. Although historically condemned as monophysite heresy, increasingly seen by Chalcedonian Christianity as closer to the aims of the Council of Chalcedon.
Monothelitism: heresy, discussed in the aftermath of the Council of Chalcedon, proposing that Christ had only one will; condemned by the Third Council of Constantinople (AD 680-81), since nothing divine in Christ substitutes for part of human nature.
Monoenergism: position, related to monothelitism, that two natures of Christ are unified in a single “energy” or activity; judged heretical by Chalcedonian churches (condemned at the Third Council of Constantinople), since it denies something human in Christ: a distinctly human mode of action.
Nestorianism: heresy stressing the distinctness of divinity and humanity in Christ, named after Nestorius (386-450), Patriarch of Constantinople. Condemned at the First Council of Ephesus (431) and the Council of Chalcedon (451), which stressed that the two natures were united in one Person in Christ; remains the characteristic Christological position of the Church of the East.
Valentinianism: complexion of Gnostic positions, but known particularly for heresy that Jesus did not take humanity from Mary but merely passed through her womb, as through a conduit.
Virgin birth: that Mary conceived Jesus as a virgin; not to be confused with immaculate conception, the proposal that Mary was preserved from the stain of original sin from her conception.