1. During the historic meeting at Anba Bishoy Monastery, Egypt, from 20th to 24th June 1989 and helped by the encouraging words and helpful prayers of His Holiness Pope Shenouda III, the official representatives of the two families of the Orthodox Churches were able to formulate their first Agreed Statement on Christology.

2. The first item in that statement was the common ground in the formula of the common father Saint Kyrill of Alexandria «Mia Physis (or Hypostasis) tou Theou Logou Sesarkomene».
It is well known to both sides that the term hypostatic union (enosis kath hypostasin) cannot mean the union of two persons since this is the Nestorian heresy.
Saint Kyrill spoke about «Hypostatic Union» and refused completely the term «Prosopic Union» although for him a hypostasis cannot exist without its own prosopon.

For him to speak about two hypostaseis means speaking about two persons.
That is why he wrote to his friend Acacius Bishop of Melitene:-
«Behold, those who fashion the confession of the true faith clearly name two natures, but maintain that the expressions of those inspired by God are divided according to the difference of the two natures. Then, how are these assertions not opposite to yours? For you do not allow the attributing of expressions to
two persons, that is, to two hypostaseis.
But, my dear friends, I would say, I have written in the propositions:
If anyone attributes to two persons, that is, to two hypostaseis, the sayings and ascribes some to a man considered separately from the Word of God, and ascribes others, as proper to God, only to the Word of God the Father, let him be condemned.» (1)
Saint Kyrill also wrote against the Nestorians in his letter to Valerian Bishop of Iconium:
«If they should say that God and man by coming together in one constituted the one Christ with the hypostasis of each obviously preserved unblended but distinguished by reason, it is possible to see that they are thinking and saying nothing accurate in this» (2)
Saint Kyrill showed his refusal to prosopic union in his second letter to Nestorius (epistula dogmatica — letter 4) and wrote:
«In no way will it be profitable that the true account of the faith mean this even if some admit the union of persons (prosopic union). For the Scripture has not said that the Word united the person of a man to himself, but that he became flesh.» (3)
But on the other side Saint Kyrill wrote in the same epistle:
«We say rather that the Word by having united to himself hypo static ally (Kath Hypostasin) flesh animated by a rational soul, inexplicably and incomprehensibly became man.» (4)
Saint Kyrill further explained :
«But if we reject the Hypostatic unity as either unattainable or improper, we fall into saying that there are two sons» (5)
The Agreed statement spoke of «the one composite (synthetos) hypostasis of our Lord Jesus Christ».
Also it spoke about «the mystery of the hypostatic union we confess in humble adoration».

The question now is to interpret the difference between the term «prosopon» (person) and the term «hypostasis» for Saint Kyrill.

The term hypostasis for Saint Kyrill meant always the personalised nature i.e. the person together with the nature he possessed.
The composite hypostasis for Saint Kyrill does not mean a composition of prosopons but rather a composition of natures in one simple prosopon (person).
The term hypostatic union (ενωσις καθ υποστασιν) for him always meant the union of natures in one simple person (prosopon).
This is why to speak about «hypostatic union» (hypostatical union) is automatically speaking about «natural union» (physical union).
That is what Saint Kyrill wrote in his third letter to Nestorius (letter 17):
«We do not think that, being made flesh, the Word is said to dwell in Him just as in those who are holy, and we do not define the indwelling in Him to be the same. But united according to nature «kata physin» κατα φυσιν and not changed into flesh, the Word produced an indwelling such as the soul of man might be said to have in its own body. (6)
Again in the same letter he wrote:
«The Word of God united, as we already said before, to flesh according to hypostasis «kath hypostasin» κατα υποστασιν is God of all and is Lord of all, and neither is he servant of himself nor master of himself. » (7)

For the same reason Saint Kyrill used both the expressions (Mia Physis tou Theou Logou sesarkomene) and (Mia Hypostasis tou Theou Logou sesarkomene), since hypostatic union for him always meant natural union.

The natural union of divinity and humanity in Jesus Christ is very important for our salvation by sacrificing his holy and divine body on the cross so that «God became my salvation» (Is. 12:2).

In order that God the Word would become man it is not sufficient for Him to put on humanity i.e. to be clothed with humanity. But the Word of God was incarnate and became Himself man while remaining God as He was. For example it is necessary for somebody in order to say «I am gold», that he should have gold as his own nature through natural union. But if he only is wearing a ring of gold, he can never say «I am gold». The Word of God incarnate said to the Jews: «me a man who has told you the truth» (John 8:40). This could never have been said unless He took our human nature and made it His own nature or His very own. Also we may notice that any human being can say I am flesh with reference to the body he owns and is united «according to nature» and «according to hypostasis» to his spirit.

Saint Kyrill wrote: «We say that the only begotten Word of God, being spirit as God, according to the Scriptures, for the salvation of men was made flesh and became man, not by transmuting a body for himself from his own nature, nor by being deprived of being what he was, nor by having sustained a change or alteration, but by taking his, undefiled body from the Holy Virgin, a body animated rationally. Thus he proved that body to be his own in an incomprehensible, unconfused and entirely ineffable union, not as the body of someone else but known as his very own. » (8)
3. The incarnate Logos is consubstantial in Godhead with the Father and consubstantial with us in manhood without sin. The two natures for Saint Kyrill continued to exist in the union and are distinguised in thought alone (refer to article no. 4).

In his second letter to Succensus Bishop of Diocaesarea in Isauria Saint Kyrill wrote:
«If we call the Only-begotten Son of God become incarnate and made man ‘one’, that does not mean he has been ‘mingled’, as they suppose; the Word’s nature has not transferred to the nature of the flesh or that of the flesh to that of the Word—no, while each element was seen to persist in its particular natural character for the reason just given, mysteriously and inexpressibly unified he displayed to us one nature (but as I said, incarnate nature) of the Son. ‘One’ is a term applied properly not only to basic single elements but to such composite entities as man compounded of soul and body. Soul and body are different kinds of thing and are not mutually consubstantial; yet united they constitute man’s single nature despite the fact that the difference in nature of the elements brought into unity is present in the composite condition. It is therefore idle for them to claim that if there is one incarnate nature of the Word it follows there must have been a mingling and merger, with the human nature being diminished by its removal. It has neither got smaller nor is it being removed (to use their terminology); for to state that he is incarnate gives completely adequate expression to the fact that he has become man. Had we kept silence on that point, their captious criticism might have had some ground; as it is, seeing that the fact that he is incarnate has of course been added, how can there be any suggestion of diminution or illicit removal? ‘If the self-same is seen as fully God and fully man, as consubstantial in Godhead with the Father and consubstantial with us in manhood, what about the fullness if the manhood no longer exists? What about the consubstantiality with us, if our substance., no longer exists?’
The answer, or explanation, in the preceding paragraph adequately covers this further point. If we had spoken of the one nature of the Word without making the overt addition ‘incarnate’, to the exclusion apparently of the divine plan, there might have been some plausibility to their pretended question about the complete humanity or the possibility of our substance’s continued existence. In view, though, of the fact that the introduction of the word ‘incarnate’ expresses completeness in manhood and our nature, they should cease leaning on that broken reed. There would be good grounds for charging anybody who deprives the Son of his complete manhood with casting overboard the divine plan and denying the incarnation; but if, as I said, to speak of his being incarnate contains a clear, unequivocal acknowledgement of his becoming man, there is no problem to seeing that the same Christ, being one and unique Son, is God and man as complete in Godhead as he is in manhood. Your Perfection expounds the rationale of our Saviour’s passion very correctly and wisely, when you insist that the Only-begotten Son of God did not personally experience bodily sufferings in his own nature, as he is seen to be and is God, but suffered in his earthly nature. Both points, indeed, must be maintained of the one true Son: the absence of divine suffering and the attribution to him of human suffering because his flesh did suffer. » (9)
In this passage Saint Kyrill explained both facts that the two natures with all its properties continued to persist in the union which formed one incarnate nature or one composite united nature or as stated in the agreed statement: «an inseparably and unconfusedly united real divine-human being» or «the natures which are united to form one composite unity».

But it should be noticed that the one nature mentioned in the teaching of Saint Kyrill does not mean that the Holy Trinity became incarnate, since the three persons of the Trinity are completely distinct from each other yet one in substance (essence) consubstantial and one in divine nature.

The union of natures of the incarnate Word of God are the union of individualized nature, or more precisely the union of personalized natures which are forming one composite hypostasis of the Incarnate Logos.

The Oriental Orthodox and the Orthodox are expressing the same reality when they speak about one composite nature or one composite hypostasis, since the composition in the hypostasis of the incarnate Word of God is the composition of natures and not that of persons.

The Oriental Orthodox are referring to the personalized nature which can be correctly named the hypostasis, but on the other hand no body can deny that it is also named a nature, but as Saint Kyrill wrote «the incarnate nature of the Logos» i.e. as personalized in the Logos and not in its Trinitarian magnitude.

4. It was stated in the agreement that the divine nature and the human nature which were united together in Jesus Christ, could be «distinguished from each other in contemplation only (ti theoria moni)».

This fact was expressed by Saint Kyrill of Alexandria in his letter to Acacius Bishop of Melitene (letter 40):

«Accordingly, whenever the manner of the Incarnation is closely considered, the human mind doubtless sees the two, ineffably and unconfusedly joined to each other in a union; but the mind in no wise divides them after they have been united, but believes and admits strongly that the one from both is God and Son and Christ and Lord.» (I0)
Saint Kyrill also wrote in the same letter:
«Wherefore, we say that the two natures were united, from which there is the one and only Son and Lord, Jesus Christ, as we accept in our thoughts; but after the union since the distinction into two is now done away with, we
believe that, there is one physis of the Son» (11)

5. The will of the Incarnate Logos:
The Agreed Statement gave a very clear solution for the debate concerning thewill of Jesus Christ as follows:
«The real union of the divine with the human, with all properties and functions of the uncreated divine nature, including natural will and natural energy, inseparably and unconfusedly united with the created human nature with all its properties and functions, including natural will and natural energy. It is the Logos incarnate who is the subject of all willing and acting of Jesus Christ. «
Two natural wills were united without confusion or separation in one person.
The natural wills of both divinity and humanity continued to exist in the union.
The natural will is an expression of the natural desire, i.e. the desire of the nature.
The personal will is an expression of the decision i.e. the decision of the person.
Since Jesus Christ is composed only of one simple free person (prosopon).
That is why He always had one decision i.e. one personal will. In this decision He was one with the Father and the Holy Spirit according to His divinity, at the same time He was obedient to the Father according to His humanity.
Our human nature was blessed in Jesus Christ, being the head of the Church,
He became a cause of salvation to all who obey Him.
6.The two energies continuted to exist in the union without confusion and
without separation.
7.Condemning both the Nestorian and Eutychian heresies:
The agreed statement said: «We agree in condemning the Nestorian and the Eutychian heresies. We neither separate nor divide the human nature in Christ from His divine nature, nor do we think that the former was absorbed in the latter and thus ceased to exist».
Historically speaking we can say that the Oriental Orthodox were fighting against the Nestorian heresy and at the same time rejecting and condemning the Eutychian heresy. On the other hand the Orthodox were fighting against the Eutychian heresy and at the same time rejecting and condemning the Nestorian heresy. Both families have worked together side by side to defend the authentic Orthodox faith. Although they were divided but were fighting together one and the same battle.
8.The two expressions: «one incarnate nature of God the Word out of two natures without change, without confusion» and «two united natures without separation, without division» can complete each other on our way to the restoration of full communion to stand together against all heresies, thus saying together «one incarnate nature of God the Word in which two natures were perfectly united and continued to exist».

9. The one incarnate nature of God the Word is not a third nature of Jesus Christ, because the nature is the sum of properties or qualities of the substance (essence) and since the two natures of Christ were united without mingling or
change, then the incarnate nature is the sum of the qualities of both His divinity and His humanity.
The natures composing the incarnte Logos continued to exist in the union and the properties of each nature were not destroyed because of the union. This fact was explained by Saint Kyrill in his second letter to Nestorius (epistle 4) as
follows:
«We say that, although the natures are different which were brought together to a true unity, there is one Christ and Son from both. The differences of the natures are not destroyed through the union, but rather the divinity and
humanity formed for us one Lord Jesus Christ and one Son through the incomprehensible and ineffable combination to a unity.» (12)
When we add two groups of things together this does not mean forming a third
group. Because the two groups are still subsisting without change but they are
really united together.

10. The Agreed Statement stressed confessing the holy Virgin Saint Mary as «Theotokos» thus the statement quotes Saint Kyrill of Alexandria:
«It is sufficient for the confession of our true and irreproachable faith to sav and to confess the holy virgin is Theotokos« (Horn. 15, cf. Ep.39)

Saint Kyrill also wrote in his second letter to Nestorius:
«He made our flesh his own, and was born man from a woman without having thrown aside his divinity and his being begotten of God the Father, but, in the assumption of flesh, he remained what he was. The doctrine of the precise faith everywhere maintains this. We shall find that the holy Fathers have thought in this way. In this way, they have not hesitated to call the Holy Virgin the Mother of God Theotokos.» (13)»

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1 Saint Cyril of Alexandria, Letter 40, par. 14, The Fathers of the Church, Volume 76, C.U. A., 1987,.
p.161.
2 ibid, letter 50 par. 5 p.214.
3 Ibid, letter 4 par. 7, p.41
4 ibid. par. 3, p.39
5 ibid par. 6, p.40,41
6 ibid letter 17 par.9p.84
7 ibid. par. 10 p.84,85
8 ibid, letter 50 par 3 p.213.
9 Cyril of Alexandria, Select Letters, Lionel R. Wickham, second letter to Succensus, par. 3,4, Oxford
At the Clarendon Press 1983, printed in both Greek and English, p. 89-91
10 Saint Cyril of Alexandria, Letter 40, par. 15, The Fathers of the Church, Volume 76, C.U.A., 1987
p.162.
11 Ibid, par. 14 p. 160.
12 ibid letter 4 par. 3 p. 39
13 ibid part7.p.41