Consubstantiation

Consubstantiation, a teaching used to explain the Christian experience and conviction that Christ is truly present with his people in their celebration of the Eucharist. Consubstantiation was developed in the Lutheran wing of the Protestant Reformation during the 16th century. The idea appears in the writings of Martin Luther; the word itself was first employed by his younger contemporary, Melanchthon.

Consubstantiation rests on the same philosophical assumptions as the medieval doctrine of transubstantiation, which it opposed. Both doctrines depend on Aristotle's teaching that matter consists of accidents, which can be perceived by the senses, and substance, which the mind grasps and which constitutes essential reality. Both agree that, in the Eucharist, the accidents of the bread and wine remain unchanged. Unlike the doctrine of transubstantiation, however, that of consubstantiation asserts that the substance of the bread and wine is also unchanged, the ubiquitous body of Christ coexisting “in, with, and under” the substance of the bread, and the blood of Christ in, with, and under the wine, by the power of the Word of God.

Luther illustrated consubstantiation by the analogy of iron put into fire: iron and fire are united in red-hot iron; yet the two substances remain unchanged.