Christology
The Communication of Attributes (Communicatio Idiomatum)
Because Christ's divine and human natures are united in one person, the properties of each nature may rightly be predicated of the one person, Jesus Christ.
The doctrine explained
The communicatio idiomatum ('communication of properties/idioms') is the Christological rule governing how language about Christ's two natures may be applied to his single person. Because the eternal Son took a human nature into personal union with himself without confusing the two natures (per Chalcedon's 'unconfused, unchanged, undivided, unseparated'), Scripture can rightly say things like 'the Son of God died' (a divine title paired with a properly human predicate, since deity as such cannot die) or 'the man Christ Jesus is worshiped as Lord' (a human designation paired with a properly divine predicate). The properties of each nature are communicated to, and truly predicated of, the single unified person, not directly to the other nature itself.
This rule is what allows Christians to say, following Acts 20:28, that God 'obtained the church with his own blood' — not because deity as such bleeds, but because the person who is truly God also truly has a human nature capable of bleeding, and it is that one person, not merely 'a nature,' who is the proper subject of every predicate, human or divine, applied to Christ. This is sometimes called the genus idiomaticum, the most widely accepted and least controversial form of the communicatio, affirmed across virtually the entire historic Christian tradition.
Lutheran theology developed two further, more controversial applications in its Eucharistic and Christological polemics against Reformed theology: the genus majestaticum, whereby divine attributes (such as omnipresence) are communicated to Christ's human nature itself, enabling that human nature to be genuinely present in, with, and under the Eucharistic elements everywhere the Supper is celebrated; and the more limited genus apotelesmaticum, concerning the joint operation of both natures in Christ's saving work. Reformed theology rejected the genus majestaticum specifically, holding that communicating a divine attribute like omnipresence to the human nature itself effectively swallows up or dissolves the reality of a genuinely local, limited human nature, violating the Chalcedonian insistence that the natures remain 'unconfused' and retain their own proper characteristics (the so-called extra Calvinisticum: the Son's divine nature is not exhaustively contained within, and continues to act 'outside' or 'beyond,' the assumed human nature even during the incarnation).
The doctrine matters practically far beyond technical Christology: it is the reason Christians can meaningfully worship Jesus as God without worshiping 'a nature' in the abstract, can speak of God's suffering and dying on the cross without either denying real deity or real human suffering, and can affirm the full weight of both 'truly God' and 'truly man' without the language collapsing into either Nestorian division (two separate subjects, dodging any interchange of properties) or Eutychian confusion (one blended nature, erasing the distinctiveness the interchange presupposes).
Biblical basis
- Acts 20:28God obtained the church with his own blood — a divine subject with a human predicate.
- 1 Corinthians 2:8The rulers of this age crucified 'the Lord of glory,' a divine title applied to one who suffered a human death.
- John 3:13The Son of Man who descended from heaven, human title paired with a claim of heavenly origin.
- Colossians 2:9In Christ the whole fullness of deity dwells bodily, grounding the unity of the two natures in one person.
- 1 Timothy 3:16God was manifested in the flesh, an early creedal-style statement of the same pattern.
How the wording developed
- 5th centuryCyril of Alexandria's Christology, later ratified at Ephesus (431) and Chalcedon (451), grounds the communicatio in the single hypostasis (person) of Christ as the proper subject of all predications.
- 451, Council of ChalcedonDefines the two-natures-one-person framework ('unconfused, unchanged, undivided, unseparated') presupposed by the classical communicatio idiomatum.
- 553, Second Council of ConstantinopleAffirms theopaschite language ('one of the Trinity suffered in the flesh') as orthodox, an important application of the communicatio against residual Nestorian hesitations.
- 1520s-1580sLutheran-Reformed Eucharistic controversies drive the detailed technical development of the genus majestaticum (Lutheran) versus the extra Calvinisticum (Reformed).
- 1577, Formula of ConcordLutheran confessional articulation of the communicatio idiomatum, including the genus majestaticum, as the basis for the ubiquity of Christ's human nature underlying Lutheran sacramental theology.
Misunderstanding vs. the actual claim
Not this: The communicatio idiomatum means Christ's human nature literally became divine or omnipotent.
But this: In the majority (Reformed, Catholic, Orthodox) reading, attributes are communicated to the person, not mixed directly into the other nature; only Lutheran theology extends certain divine attributes to the human nature itself, and even then in a qualified, non-natural (personal, gift-like) sense.
Not this: Saying 'God died on the cross' means the divine nature itself ceased to exist or was extinguished.
But this: It means the person who is God, in his human nature, underwent death; the divine nature, incapable of death or corruption, was not itself thereby ended.
Not this: This is a minor technical dispute with no practical importance for ordinary Christian worship.
But this: It underlies the ability to worship Jesus as fully God and fully man at once, and it directly shaped major historical divisions over the Lord's Supper still reflected in different denominations' practice today.
Where Christians differ
- • All Chalcedonian traditions affirm the basic genus idiomaticum: properties of both natures are truly predicated of the one person of Christ.
- • Lutheran theology additionally affirms the genus majestaticum, communicating divine attributes such as omnipresence to Christ's human nature, undergirding its view of the Eucharist.
- • Reformed theology denies the genus majestaticum, holding the extra Calvinisticum: the Son's divine nature is not confined to, or dissolved into, the human nature, even in personal union.
- • Oriental Orthodox (miaphysite) traditions, while rejecting the Chalcedonian 'two natures' formula in favor of 'one incarnate nature of the Word,' arguably intend to safeguard a similar underlying unity of subject, though the Chalcedonian/non-Chalcedonian divide over the correct technical vocabulary persists to this day.
The hardest question
If divine attributes such as omnipresence are genuinely communicated to Christ's human nature (the Lutheran genus majestaticum), in what sense does that nature remain a real, limited human nature at all rather than being effectively absorbed into divine infinity, and if instead such communication is denied (the Reformed extra Calvinisticum), does bodily localizing the human nature to one place at a time compromise the Chalcedonian insistence on one undivided person acting as a genuine unity in every act, including the Eucharistic presence each tradition wants to affirm in its own way?
For further study
Primary and secondary sources on both sides of this question. Reading the strongest opposing case is part of the work, not a concession.
Lord Jesus Christ: Devotion to Jesus in Earliest Christianity — Larry Hurtado
The definitive study of how quickly Jesus was worshipped, based on the earliest evidence.
The Incarnation of God — Thomas Weinandy
A careful account of Chalcedonian two-natures Christology and the objections against it.
The Myth of God Incarnate — John Hick (ed.)
The classic revisionist challenge to incarnation doctrine; the position orthodox Christology must answer.
Jesus and Judaism — E. P. Sanders
The historical-Jesus framework most contemporary scholarship still works within.