COMMUNICATIO IDIOMATUM (interchange of properties)

A term applied to the person of Christ by those in the early church who believed that although the human and divine natures remained separate, the attributes of the one could be applied to the other. Thus the divine Word could be described as dying on the cross and the Virgin Mary was the mother of God (Theotokos).

The idea of communicatio idiomatum was anticipated by OF ANTIOCH in the early second century and was taken up by the Alexandrian school of theologians: I, Apollinarius, GREGORY OF NAZIANZUS, GREGORY OF NYSSA, CYRIL OF ALEXANDRIA, and THE GREAT, among others.

Cyril exploited it to the fullest extent, stating, “ has imparted the glory of the divine operation to His own flesh, while at the same time taking to Himself what belongs to the flesh.” The doctrine received conciliar authority in the Tome of Pope I (449), accepted by the Council of CHALCEDON.

There, at the sixth session, held on 25 October 451, the council drafted a Christological definition that asserted: “Our Jesus Christ is to us one and the same son, the self-same Perfect in Godhead, the self-same Perfect in manhood, truly God and truly man . . . the difference of the Natures [of Christ] being in no way removed because of the Union, but rather the properties of each nature being preserved into one Prosopon and one Hypostasis.”

In later times, in Lutheran circles, the doctrine was understood in a way not in harmony with Leo. In Byzantium, on the other hand, the doctrine was extended to cover the relations of church and state.

Opposed to the Alexandrian idea were theologians of the Antiochene school (Eustathius, Diodore of Tarsus, and THEODORE OF MOPSUESTIA, among others). They emphasized the concrete human life of the historical Jesus. Certain thinkers held that there were two Sons—the Son of God and the Son of Man—whose union was not due to a fusion of with the flesh—rather, the Word dwelt in the flesh as in a temple, much as God indwelt His prophets. The human nature of Jesus underwent real growth in knowledge and in the discernment of good and evil.

MONOPHYSITISM, as held by the Coptic church, is a development of Alexandrian theology that rejected the communicatio, as it did as a whole. Now that controversies have become less pronounced, the doctrine of communicatio idiomatum may yet find favor in circles.


  • Bethune-Baker, J. F. An Introduction to the Early History of Christian Doctrine. London, 1949.
  • Boularand, E. “La théologie antiochienne.” Bulletine de Littérature ecclésiastique 68 (1967):241-72.
  • Frend, W. H. C. The Rise of the Monophysite Movement. 2nd ed. Cambridge, 1979.
  • Kelly, J. N. D. Early Christian Doctrines. London, 1958. Sellers, R. V. Two Ancient Christologies. London, 1940.