Throughout the entire treatise of the unity of Christ one cannot evade the strong, determined, and authoritive voice of St Cyril. The entire work is a mysterious dialogue because it is between an anonymous friend called ‘B’ and Cyril himself, referred to as ‘A’. The conversation between the pair covers many issues, some more prominent than others however the major theme discussed in the work is Cyril’s Christology of Christ as God-man. He firstly discusses within his treatise the major issue concerning the hypostatic union of the two natures, and then he brings to the reader’s attention the validity of the Theotokos title. The contents therefore within the treatise of the unity of Christ would prove to be a means of a complex Christological contemplation on the hypostasis of the Divine and human natures of Christ.

The Unity of Christ as a Hypostatic union

The most discussed theme throughout the treatise seems to be the dispute of the Divine (ὐποστάσις)[2] hypostasis, unites to Himself the human nature.  St Cyril here and on numerous occasions responds to his friend ‘B’ against the heretical teaching of Nestorius. Cyril would argue against Nestorius that both natures of Christ must be hypostasized which meant that after the incarnation the two natures were not separate realities, but were both in the one Christ. By no means would Cyril agree that Christ would have two hypostasies as Nestorius would claim because this would allude to a teaching of two Sons.[3]

According to Cyril, Jesus’ two natures, human and divine, are inseparable, Jesus will forever be the God-man, fully God and fully human, two distinct natures in one Person (p77.) Jesus’ humanity and divinity are not mixed, but are united without loss of separate identity. Jesus sometimes operated with the limitations of humanity (John 4:6; 19:28) and other times in the power of His deity (John 11:43; Matthew 14:18-21).

For Cyril, the hypostatic unity of the two natures was a crucial significance, as Christ being One (p.77). In reflecting upon this we see Cyril clarify this thoroughly: ‘how wicked they are, when they divide in two the one true and natural Son incarnated and made man, and reject the union’ (p.74). Cyril makes it clear that there are no separate realities between the two natures, but one hypostasis: ‘I say that we must call him God made man, and that both the one and the other are this same reality’ (p.76.) Furthermore Cyril articulates his point of hypostatic unity when his friend ‘B’ raises the issue concerning the separate realities: ‘they are not separated…on the contrary they are brought together into an (ἔνωσιν ἀδιάτμητον[4]) indissoluble union (p.77.)

In light of this Cyril further down in the treatise responds to a question from his friend ‘B’ which concerns the two natures: ‘but in the case of Christ they came together in a mysterious and incomprehensible union without συγχύσεως[5] confusion[6] or change (p.77.) Throughout the history of doctrine this was to be a pivotal point of Orthodox Christology. Cyril was determined to expose Nestorius’ teachings as misleading and dangerous. This was the reason that instigated the ecumenical council at Chalcedon in 454[7] and in which Nestorius was anathematized.

McGuckin summarized Cyril’s perspective on the hypostatic union, he said: ‘for Cyril the union of two distinct levels of reality, Godhead and manhood takes place dynamically because there is only one individual subject presiding over both, the one person of the incarnate deity.’[8] Other scholars like Russell agree with this Christological view, but also support Cyril’s strong defiance against Nestorius’ criticism:

He brushes aside the Alexandrian complaints that Nestorius is purporting to review, and then he sets out a succinct statement of Christ’ single subject Christology. The word was not changed into flesh or transformed into a human being but was united (κάθυπόστασιν[9]) hypostatically.

Likewise we see a further similar perspective of this hypostasis theory of Cyril’s: ‘the Son is as perfect in His humanity as in His Divinity, because he is simultaneously God and man…the hypostasis are not to be divided or separated from one another.’[10] We learn from this quote that McKinnon is declaring his support for the one hypostasis from the two natures.

In addition to Mckinnons’ agreement on the theory, we see that Cyril’s hypostatic theory is also supported within a recent journal: ‘for Cyril [hypostasis] signified the subject to whom attributes and operations can be applied within the true substantial unity i.e. the true existing individual.’[11]

Hence, one can declare that there is much support and defence for Cyril’s hypostatic union of the two natures. For Cyril, Christ was at once Divine and human, inseparably so.

Soul and Body: An analogy of unity in Distinction

Cyril’s most favourite analogy of the union of the Divinity and Humanity in Christ is consequently a way of union of body and soul in humanity. For Cyril the image of the soul and body expressed the (διαίρετον[12]) (a division[13]) two separate natures, which can be intertwined with one another without damaging the reality of both. This definitely was an important Christological principle for Cyril. Cyril convey’s this throughout his discussion in the treatise:

We must admit of course, that the body which He united to Himself was endowed with a rational soul, for the Word, who is God would hardly neglect our finer part, the soul and have regard only for the earthly body. (p.64).

In another section of the text, Cyril shows the aspect of body and soul from a response to a question from his friend: ‘ even though [Christ]  is not homogenised but really composed of two things, soul and body. (p.78).

McGuckin would quite clearly agree to this claim by stating Cyril’s thought as: ‘the analogy of the soul and body of man would demonstrate that two distinct subjects can be united together without destroying or compromising the integrity of the other.’[14] Cyril would assert that such a union of the two realities trigger a dynamic interpretation. Cyril declares whatever a human person would undertake with the body and soul would do so through an uninterrupted unification. 

McKinnon seems to have the same opinion with that of Cyril and would show that the union of Christ is an image of body and soul: ‘the Word of God is united ineffably to flesh endowed with a rational human soul, and there is consequently one Son, Christ and Lord.’[15]

Suffering Christ, Divine Impassibility

The union of the two natures not only shows a way of the soul and body unity, but echoes also a manner of God incarnate suffering and not in His Divine nature. Through the hypostatic unity Christ is able to sanction His human nature to undergo suffering without conflicting His Divinity. Cyril supports such a claim in that the Word of God suffers in His human state and that His divine nature remains impassible[16] (p.117) (ἀπαθής[17]). Within the treatise there is an indication of this aspect: ‘since the manner of the economy allows him to blamelessly choose to suffer in the flesh and not to suffer in the Godhead.’ (p.118). Moreover Cyril conveys’ his argument at another part of his discussion with his friend ‘B’: ‘[Christ] is said to suffer in the flesh, even so he retains his impassibility as he is understood as God’ (p.117). On another occasion St Cyril gives a further testimony to the impassible Christ: ‘he suffers in His own flesh, and not in the nature of the Godhead’ (p.130).

With numerous accounts in the main text testifying to the divine nature not suffering within the unity of Christ, such an assertion is also cited by other sources: ‘God suffers in so far as his own body suffers, for he does not suffer in his deity, he suffers in his humanity which he appropriated as his own.’[18] In light of this there is further support given for this Christological claim of St Cyril concerning impassibility of the Divinity of Christ: ‘the word suffered in his own flesh, but did not suffer in the nature of the Divinity, as he is impassible God.’[19] In light of this we see quite interestingly that according to Gavrilyuk there seems to be a striking relevance to this aspect from a Nestorian point of view within a confession of faith:

For the Divine substance cannot fall under the necessity of change and suffering, because if the Godhead underwent change, there would no longer be a revelation but a corruption of Godhead and manhood, and there would no longer be salvation.[20]

Clearly this passage of the Nestorian confession of faith shows that there is an exclusion of any such possibility of the Divine element interacting in the suffering of the human nature of Christ. Nestorius’ support for the impassible Divine nature would indicate that he is supporting a part of Cyrils’ Christological doctrine!

Similarly in another section of Gavrilyuk’s book we see a corresponding perspective to these claims of impassibility: ‘it was impossible for the Divinity to participate any way in the properties of humanity.’[21]

On the Title Theotokos

Throughout the dialogue Cyril’s anonymous friend ‘B’ speaks of (χριστοτόκον)[22] (p.52) the ‘Mother of Christ’ as Christ bearing  this was employed by Nestorius in place of θεοτόκος which he rejected (p.52). Cyril’s friend ‘B’ indicates this in the text: ‘he [Nestorius] denies that the Holy Virgin is the Mother of God and calls her the Mother of Christ’ (p.52). Fr Doru clarifies what Nestorius meant by his claim: ‘that the Holy Virgin has given birth to a mere man…and since she bore a perfect human person there was no justifiable reason for her to be called Theotokos.”[23]

In the treatise, it is evident that St Cyril was irritated at such claims, referring to Nestorius’ character as someone who is disturbed and confused, and accuses Nestorius’ teaching as heretical: ‘these are the teachings of a wanderer, of a sick mind that has strayed’ (p.53).

St Cyril shows a series of questions within the dialogue as to make his friend understand the notion of the Theotokos: ‘then why did the Word who is God make a virgin the mother of his own flesh with a (κυοφορούσαν[24]) conception a pregnancy[25] straight from the Holy Spirit?’ (p.62). Furthermore Cyril conveys to his friend ‘B’ a further question of the same nature: ‘if they really believed that he was God, then why would they be afraid of calling her who gave him birth ‘Mother of God- I mean after the flesh?’ (p.64). According to O’Keefe he claims that to reject the title Theotokos is like joining forces with another heresy:

The denial of the Theotokos is logically the same as Arianism, those who refuse to confess that Mary is the Mother of God, do not appreciate the fullness of the Son’s participation with us, just as the Arians misunderstood the fullness of the Son’s participation in God.[26]

The quote above makes an interesting point, because if Nestorius was saying that Jesus was a perfect man, only a man, then he may have been implying the Arian view that He was only a Divine creation from God and not God Himself. However this idea seems conflicting with his theory of impassibility because God alone is impassible.

Cyril’s upholding of the title Theotokos is the safeguard to the true union of God and man in Christ, because it excludes the idea that Christ is either merely a God bearing man or a God who simply uses the body as an instrument.


The unity of Christ by St Cyril is a powerful teaching. The unity of Christ is a notion of interchange and transformation, in which God has inaugurated its purpose for transfiguration. Cyril’s Christology is certainly a paradigm for the life of each and every contemporary Christian of today. We uphold in every Divine Liturgy the ideas of union expressed by St Cyril when we hear the hymn of the only begotten Son and Word of God. The unity of the two natures of Christ is an example of the relationship we ought to embrace with God (p.74). The evilness and confused sayings of Nestorius (p.51) signifies the way by which we who live within the church can be caught up in the snares and traps of the devil from a delusional mind which lead us to spiritual darkness. Cyril’s Christological thought shows that God is not just united with a human being, but with all humanity (1 Tim 2:5). For this reason the unity of Christ is a reflection of the relationship which was always meant to exist between humanity and God. Cyril throughout this treatise is quite successful as he clears up the meaning of the two natures of Christ within a paradoxical union.


Costache, D.  “Fifth Century Christology between Soteriological Perspective and Metaphysical Concerns: Notes on the Nestorian Controversy”. Phronema 21 (2006): 47-59.

Florovsky, G. The Byzantine Fathers of the Fifth Century. Vaduz: Buchervertriebsanstalt, 1987.

Gavrilyuk, Paul. The Suffering of the Impassible God: The Dialects of Patristic Thought. Oxford: Oxford University Press, 2004.

Kalantzis, George. “Is there Room for two? Cyril’s Single Subjectivity and the Prosopic Union”. SVTQ  52:1  (2008) :95-110.

Κυρίλλου Αλεξανδρείας, ‘Οτι είς Χριστός’, in Περί Της Αγίας και Ομοούσιου Τριάδος Λόγοι ΣΤ’ – Z’ Περι Ενανθρωπήσεως του Μονογενούς, ed. Γ. Μερετάκης Θεσσαλονίκη: Πατερική Ἑκδοσεις Γρηγόριος ο Πάλαμας, 2002.

Lampe,  G. W. H.W A Patristic Greek Lexicon. Oxford: Oxford University Press & Clarendon Press, 1961.

McGuckin, John. Saint Cyril of Alexandria and the Christological Controversy. Crestwood, NY: SVS Press, 2004.

McKinnon, S.A  Words, Imagery, and the Mystery of Christ: A Reconstruction of Cyril of Alexandria’s Christology Leiden, Boston, Koln: Brill, 2000.

O’Keefe, J.J. “Impassible Suffering? Divine Passion and Fifth Century Christology”. Theological Studies 58 (1997): 39-60.

Parry, K. et al. The Blackwell Dictionary of Eastern Christianity. Massachusetts: Blackwell Publishers, 1999.

Russell, Norman. Cyril of Alexandria. London & New York: Routledge, 2000.

St Cyril of Alexandria.  On the Unity of Christ. Trans. By J.A. McGuckin. Crestwood, NY: SVS Press, 1995.

[1] St Cyril of Alexandria, On the Unity of Christ, trans. John Anthony McGuckin (Crestwood, NY: SVS Press, 1995).

[2] Cyril is concerned to present Christ as one person, who has taken human nature and become incarnate according to Lampe, 1459.

[3] Nestorius argued that Christ had both the Divine and human natures, but with two separate hypostasis. Whereas Cyril argued that Christ had both natures, but one hypostasis according to McGuckin, 141.

[4] Κυρίλλου Αλεξανδρείας, ‘Οτι είς Χριστός’, in Περί Της Αγίας και Ομοούσιου Τριάδος (Λόγοι ΣΤ’ – Z’) Περι Ενανθρωπήσεως του Μονογενούς, ed. Γ. Μερετάκης (Θεσσαλονίκη: Πατερική Ἑκδοσεις Γρηγόριος ο Πάλαμας, 2002), 328.

[5] G.W.H. Lampe, ‘συγχύσεως’, in a Patristic Greek Lexicon (Oxford: Oxford University Press & Clarendon Press, 1961), 1276.

[6] Lampe, op. Cit. 1669.

[7] Ken Parry, ed., The Blackwell Dictionary of Eastern Christianity (Ma: Blackwell Publishers, 1999), 171.

[8] John McGuckin, Saint Cyril of Alexandria and the Christological Controversy (Crestwood,NY: SVS Press, 2004), 212.

[9] Norman Russell, Cyril of Alexandria (London &New York: Routledge, 2000), 36.

[10] Steven A McKinnon, Words, Imagery, and the Mystery of Christ: A Reconstruction of Cyril of Alexandria’s Christology (Leiden,Boston,Koln: Brill, 2000), 176.

[11] George Kalantzis, ‘Is there Room for two? Cyril’s Single Subjectivity and the Prosopic Union’, St Vladimir’s Theological Quarterly 52 (2008): 98.

[12] Ibid, 328.

[13] Lampe, op. Cit. 348.

[14] McGuckin, op. Cit. 212.

[15] McKinnon, op. Cit. 193.

[16] Lampe, op. Cit. 170.

[17] Κυρίλλου, op.cit.  398.

[18] McGuckin, op. Cit. 202.

[19] McKinnon, op. Cit. 217.

[20] Paul Gavrilyuk, the Suffering of the Impassible God: The Dialects of Patristic Thought (Oxford:OxfordUniversity Press, 2004), 143.

[21] Ibid, 143.

[22] Lampe,  op. Cit. 1532.

[23] Reverend Dr Doru Costache, ‘Fifth Century Christology Between Soteriological Perspective and Metaphysical Concerns: Notes on the Nestorian Controversy’, Phronema 21 (2006): 48-49.

[24] Κυρίλλου, op. Cit. 302

[25] Lampe, op. Cit. 785.

[26] John. J. O’Keefe, ‘Impassible Suffering? Divine Passion and Fifth Century Christology’, Theological Studies 58 (1997): 44-45.

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  1. For those who do not know Maltese, the translation of the comment made by the weblog of the Centre of Mary Mother of the Church Doctrine, said the following:

    “Bravo Cyril … The synod of Ephesus, in the year 431 declared Mary, OMMA (Mother of) Jesus, we can call Theotokos (θεοτόκος), Greek word that means “gave birth to God” or “Mother God”, having scrutinized teaching of St. Cyril of Alexandria.”

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