It will be remembered that Cyril’s great passion was the Nicene Creed, of which he felt his own theological work continued to expand the implications. Cyril’s understanding of the hypostatic union was that the two elements of Christ (human and divine) came together in a single physis, a single objective reality formed by a personal union [see the previous post, Christ, the Word Made Flesh in Personal Union]. Accordingly, Cyril rejected the terminology of “two natures” because, falsely thinking that the formula “one incarnate nature of the divine Word” was originated by Athanasius (it was actually Apollinarian), he was led to believe that “two natures” implied a separation within Christ–a separation between the eternal Word who descended upon Mary and the flesh born of Mary’s womb.
At Chalcedon, which vigorously rejected the position of Eutyches that “before the Incarnation Christ was of two natures, but after it there was one Christ, one Son, one Lord in one hypostasis and one prosopon,” Cyril’s basic views had carried the day. However, the Apollinarian formula “one incarnate nature of the divine word” which Cyril had mistakenly believed to be Athanasian was rejected by Chalcedon. Correcting a long-standing problem in Christological thought, Chalcedon made a clear distinction between person and nature: Christ has two natures, but is one person.
Cyril had died in 444, seven years before Chalcedon. After Chalcedon, a militant sect of his followers led by Timothy the Cat and Peter the Hoarse so staunchly adhered to the “one incarnate nature of the Divine Word” formula that they suspected Chalcedon of tacit Nestorianism. For them, it was a problem that the Definition did not mention the hypostatic union and that it did not clearly say that Christ existed “out of two” disparate elements. Again, the chief problem was that for the Cyrillians “nature” was nearly synonymous with “person;” to say that Christ had “two natures” was thus to say that He was two persons, or two Christs–and this was perceived to be Nestorian. The Cyrillians, believing themselves to be merely developing the implications of Nicea, held that
without change in His divinity the eternal Word, consubstantial with the Father, truly became man in Jesus Christ. The Word was one and the same person before and after the Incarnation, for the same person became through a personal, a hypostatic union, incarnate. This is what the Council of Chalcedon had not clearly declared: that the person of the union was the pre-existent person of the Word. The Word was united to flesh consubstantial with ours, consisting of a body and rational soul, for we could not have been saved if the Savior wree not in all things, sin alone excepted, like to His brethren. Jesus Christ is thus “out of two,” out of Godhead and out of manhood, and in their union in His one person, each remains in its reality, inseparable, but perceived as different through intellectual analysis.
Thus were the terminological and metaphysical subtleties that gave rise to the next great heresy, Monophysitism. Political causes also intervened, particularly in what came to be known as the Acacian Schism. Some notes on this, and the development of Monophysitism, will appear in a subsequent entry.