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The Most Important Church Father You’ve Never Heard Of

Many evangelical Christians have heard of Athanasius, Augustine, Irenaeus, perhaps even Tertullian or John Chrysostom. Cyril of Alexandria (A.D. 376–444), on the other hand, is not a name with which most Christians are familiar. He was, however, arguably one of the three or four most theologically influential figures in the early church, and regarding Christology, he was perhaps the most influential figure. Cyril was the Patriarch of Alexandria in Egypt from 412 until his death in 444. He had been in this position for sixteen years when Nestorius became Patriarch of Constantinople in 428. He was, therefore, the leader of the church in Alexandria when Nestorius’s criticism of those attributing the title theotokos (“mother of God”) to Mary sparked a controversy whose reverberations would be felt for generations. Cyril’s written responses to Nestorius were to have an influence that he could scarcely have anticipated.

Cyril’s Theology

Cyril’s Christology was already established before the controversy with Nestorius, but the controversy forced him to express his views as clearly as possible. In order to understand Cyril’s developed Christology, it is, therefore, helpful to have some grasp of Nestorius’s doctrine. Nestorius’s teaching followed a theological trajectory set by Diodore of Tarsus and his student Theodore of Mopsuestia both of whom advocated, sometimes explicitly and sometimes implicitly, a dual-subject Christology in which the Son of God and the Son of Mary were not identified but instead considered distinct and separate subjects.[1] Nestorius was a student of Theodore of Mopsuestia, and the influence of both Theodore and Diodore can be detected in Nestorius’s theology. He too advocated a dual-subject Christology.[2] This is why he rejected the theotokos. Mary can only be spoken of as the mother of the man Jesus, he argued. She is not the mother of the Son of God. The Son of God and the Son of Mary are distinct in Nestorius’s eyes.

In popular works, Nestorianism is often defined as the idea that Christ is “two persons.” While it is probably inaccurate to attribute this specific idea to Nestorius himself, that which he did teach is equally unorthodox.[3] Nestorius’s emphasis on the difference between the two natures in Christ led him to describe the incarnation in ways that were clearly unsound and profoundly unbiblical. In his first sermon against the theotokos, for example, he writes, “If you want to lift up someone who is lying down, do you not touch body with body and, by joining yourself to the other person, lift up the hurt one while you, joined to him in this fashion, remain what you were? This is the way to think of the mystery of the incarnation. . . .”[4] Nestorius here compares the union of the two natures in Christ to a hug. As this comment makes abundantly clear, Cyril’s response to Nestorius and the theological tradition out of which he came was absolutely necessary if orthodox Christianity was to be preserved.

In direct contrast with Nestorius, Theodore, and Diodore, Cyril of Alexandria insisted on a single-subject Christology. According to Cyril, both Scripture and the Church’s Nicene Creed make it clear that the divine Son, the second Person of the Trinity, is the one subject who became incarnate. He argued that it was this One, the Second Person of the Trinity, who was “made flesh and dwelt among us” (John 1:14). He argued that according to the Nicene Creed, we believe in “one Lord Jesus Christ, the only-begotten Son of God,” and that it is this one, only-begotten Son of God “who, for us men for our salvation, came down from heaven, and was incarnate by the Holy Spirit of the virgin Mary, and was made man, and was crucified also for us under Pontius Pilate.”[5]

When we read the Gospels, according to Cyril, we do not see the Son of Mary saying and doing some things while we see the Son of God saying and doing others. The one we encounter in the Gospels is this one, eternal, divine Son who assumed a true human nature and dwelt among us. Therefore, according to Cyril, it is proper to use the title theotokos, not because the divine nature came into being through Mary, but because the one born to Mary is God incarnate.[6] So, whereas Nestorius proclaimed, “I refuse to acknowledge as God, an infant of two or three months old,” Cyril’s theology was consistent with the worship of the infant Christ described in Scripture (e.g., Matt. 2:1–2).[7]

Cyril explained the union of the two natures in Christ using the idea of a “hypostatic” union in which the second hypostasis of the Trinity (the One eternal Son) who has a perfect divine nature from all eternity, assumed a true and complete human nature in the womb of Mary. Thus after the incarnation, the one hypostasis (the one Person, the single subject), now has two natures (divine and human). This explains why the Gospels can attribute to the one Person acts and words proper to the human nature as well as acts and words proper to the divine nature. Anything that can be predicated of either nature can be predicated of the one Person because both natures truly belong to the one Person. The attributes of either nature, however, cannot be predicated of the other nature. Cyril argued, therefore, that we do not say that the divine nature can be born, hunger, thirst, or suffer, or die. Nor do we say that Christ’s human nature has existed eternally. But we can predicate all of these things of the one Person. The hypostatic union also helps us to understand why Scripture will sometimes predicate something proper to one nature to the one Person while referring to the one Person with a name that is proper to the other nature. As the Westminster Confession of Faith explains, “by reason of the unity of the person, that which is proper to one nature, is sometimes in Scripture attributed to the person denominated by the other nature” (WCF 8.7). Thus Acts 20:28, for example, can speak of the blood of God, and Paul, in 1 Corinthians 2:8 can speak of those who “crucified the Lord of glory.”[8]

Cyril's Significance

Cyril was the most vocal and the most theologically astute critic of Nestorius and Nestorius’s supporters, and he immediately recognized that a denial of the title theotokos was an implicit denial of the deity of Christ. The writings Cyril produced during this controversy in response to Nestorius were to have a profound effect on the theology of the church. His theological influence may be measured by the impact he had on three separate ecumenical councils that dealt with various aspects of the Christological controversy.[9] The Third Ecumenical Council (the Council of Ephesus) met in 431 to deal specifically with the Nestorian crisis. The council proclaimed the Christology of Cyril to be biblical, and it condemned the teaching of Nestorius and his supporters.

The Fourth Ecumenical Council (the Council of Chalcedon), which met in 451, several years after Cyril’s death, also confirmed Cyril’s Christology.[10] In its famous Definition, Chalcedon received as statements of orthodox Christology two of Cyril’s letters to Nestorius and his letter to John of Antioch along with one letter by Pope Leo (the Tome of Leo). The Council of Chalcedon explicitly states that the Council receives these letters by Cyril and Leo “for the sake of refuting the follies of Nestorius and for the instruction of those who, in religious zeal, seek understanding of the saving Symbol”[11] In other words, according to the Council of Chalcedon, if one desires to understand the Christological teaching of the Nicene Creed, one should read these letters of Cyril along with the Tome of Leo.[12] These letters, then, provide important context for understanding the doctrinal teaching of Chalcedon.

The Fifth Ecumenical Council (the Second Council of Constantinople) met in 553 and reaffirmed the Christology of Ephesus and Chalcedon. Even though this council met over a century after Cyril’s death, his influence can still be seen in the council’s official documents. In its doctrinal declarations, the Council defended as orthodox the most controversial portion of Cyril’s third letter to Nestorius (the so-called twelve chapters or twelve anathemas).[13] In short, the doctrine of Christ found in the writings of Cyril and hammered out during his controversy with Nestorius is the doctrine of Christ defended and taught in the dogmatic teaching of three ecumenical councils.

The influence of Cyril on orthodox Christology becomes even clearer when we compare the well-known penultimate paragraph of the Definition of Chalcedon with the writings of Cyril himself. For example, in his First Letter to Succensus (ca. 434–438), Cyril writes, “We unite the Word of God the Father to the holy flesh endowed with a rational soul, in an ineffable way that transcends understanding, without confusion, without change, and without alteration, and we thereby confess One Son and Christ…”[14] Cyril uses the adverbs asynchytos, atreptos, and ametabletos. The first of these words means “unconfused” or “distinct.” The other two words are basically synonymous and mean “immutable” or “unchangeable.” The Definition of Chalcedon teaches that the two natures are united in the one Person of Christ “unconfusedly, unalterably, undividedly, inseparably.”[15] The adverbs used are asynchytos, atreptos, adiairetos, and achoristos. The first two are identical to the first two adverbs Cyril used. It appears that Chalcedon left out the word ametabletos because it is synonymous with atreptos. These first two words are used by Chalcedon to refute Eutychianism. The last two adverbs used by Chalcedon, while not used in Cyril’s sentence in the Letter to Succensus, sum up everything Cyril ever wrote against Nestorius. Cyril argued repeatedly against Nestorius that the two natures in Christ are united “without division” and “without separation” and the words adiairetos, and achoristos express that basic Cyrillian idea concisely. Chalcedon also affirmed Cyril’s doctrine of hypostatic union as well as the propriety of the use of the title theotokos.

It is not an exaggeration to say, therefore, that if one looks to the Definition of Chalcedon (as well as to the councils of Ephesus and Second Constantinople) for the contours of his Christology, he is looking to Cyril of Alexandria for the contours of his Christology. These three ecumenical councils viewed Cyril’s teaching as the most accurate expression of the Christology found in the Scriptures, so they used his works to help them express precisely the parameters of orthodoxy. This is why Cyril of Alexandria may be the most important church father many Christians have never heard of.[16]

There truly is nothing new under the sun, and the same errors that plagued the church during the fourth and fifth centuries continue to plague the church today. The biblical doctrine of Christ continues to come under fire. Those seeking the biblical and theological tools to combat the contemporary restatement of ancient heresies and contemporary denials of orthodoxy would do well to revisit the works of Cyril of Alexandria.


[1] For a short summary of Diodore’s thought, see Christopher Beeley, The Unity of Christ: Continuity and Conflict in Patristic Tradition (New Haven: Yale University Press, 2012), 179–82. For a more thorough examination of both Diodore and Theodore, see John Behr, ed. The Case Against Diodore and Theodore: Texts and Their Contexts(Oxford: Oxford University Press, 2011). [2] I am borrowing the language of dual subjectivity and single subjectivity from John McGuckin’s Saint Cyril of Alexandria and the Christological Controversy (Crestwood, NY: SVS Press, 2004). See also, Aaron Riches, Ecce Homo: On the Divine Unity of Christ (Grand Rapids: Eerdmans, 2016), 31. [3] I say “probably” because Nestorius’s actual Christology is notoriously difficult to interpret. Whether Nestorius taught that Christ is two “persons” is up for debate, but there is no doubt that what he clearly did teach was heretical and destroyed the biblical concept of a true incarnation. His doctrine of a “prosopic union” turns the incarnation into little more than an optical illusion. [4] Richard A. Norris, Jr., ed. The Christological Controversy (Philadelphia: Fortress Press, 1980), 125. [5] On Cyril’s Christology, see Thomas Weinandy, “Cyril and the Mystery of the Incarnation.” In The Theology of St. Cyril of Alexandria: A Critical Appreciation, ed. Thomas G. Weinandy and Daniel A. Keating (London: T&T Clark, 2003), 23–54; McGuckin, Saint Cyril of Alexandria, 175–226; and Hans Van Loon, The Dyophysite Christology of Cyril of Alexandria (Leiden: Brill, 2009). Weinandy, following Barth and Torrance, believes that Christ assumed a fallen human nature, and he anachronistically reads this idea into Cyril (as well as other church fathers), but in spite of this, his chapter remains a helpful introduction. [6] See Cyril’s Second Letter to Nestorius. [7] The comment by Nestorius regarding the worship of the infant Christ is quoted in McGuckin, Saint Cyril of Alexandria, 64. [8] For a standard Reformed explanation of the communicatio idiomatum, see Charles Hodge, Systematic Theology (Grand Rapids: Eerdmans, 1965), 2:392–5. [9] For a good introduction to the life of Cyril and his involvement in the controversy with Nestorius, see McGuckin, Saint Cyril of Alexandria and the Christological Controversy, 1–125. [10] Riches, Ecce Homo, 55–6. [11] This translation of the Definition of Chalcedon is found in Norris, Jr., The Christological Controversy. On the importance of Cyril’s letters, see also Timothy Pawl, In Defense of Conciliar Christology: A Philosophical Essay (Oxford: Oxford University Press, 2016), 12. [12] Translations of these letters by Cyril may be found in McGuckin, Saint Cyril of Alexandria and in John I. McEnerney, ed. St. Cyril of Alexandria, Letters 1–50, The Fathers of the Church, vol. 76 (Washington, D.C.: CUA Press, 1987). A translation of the Tome of Leo may be found in Norris, The Christological Controversy. [13] Thirteenth Anathema Against the Three Chapters, Second Council of Constantinople, AD 553. For a concise introduction to the events surrounding each of the ecumenical councils, see Leo Donald Davis, The First Seven Ecumenical Councils (325–787): Their History and Theology (Collegeville, MN: The Liturgical Press, 1983). [14] An English translation of this letter is found in McGuckin, Saint Cyril of Alexandria and the Christological Controversy, pp. 352–358. This quote is found in paragraph 6. [15] Norris, The Christological Controversy, 158. [16] This does not explain why Cyril is not as well-known as other church fathers, but that is a question for another day.


Public Domain Image: Fourth Ecumenical Council of Chalcedon by Vasily Surikov (1876; Saint Petersburg, Russian Federation).

This blog was originally posted at Tabletalk Online

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