Two Families of Orthodox
The following is excerpted from the website of the Coptic Orthodox Church of Alexandria, Diocese of Los Angeles, Southern California and Hawaii (http://lacopts.org/orthodoxy/orthodox-life/two-families-of-orthodox/)
For over fifteen hundred years [since the Council of Chalcedon in AD 451] the Eastern (Byzantine) Orthodox churches and the Oriental Orthodox churches have remained separated. Only thirty years ago they came together for the first of four unofficial theological consultations : Aarhus (1964), Bristol (1967), Geneva (1970) and Addis Ababa (1971).
These were followed by the establishment of a Joint Commission of the Theological Dialogue between the Orthodox Church and the Oriental Orthodox Churches, which has held four meetings : Chambesy, Geneva (December 1985), Anba Bishoy monastery, Egypt (June 1989), Chambesy II (September 1990) and Chambesy III (November 1993). Ignorance of the remarkable advance towards the eventual reunion of the “two families” is still widespread and it is a sad reflection on the lack of understanding of what has been agreed already that some journals, commenting on the recent reception of the British Orthodox Church by the Coptic Orthodox Patriarchate, are still impugning the Orthodoxy of the Oriental Orthodox churches with accusations of the Monophysite heresy.
There is, of course, always the zealot fringe, which has rather foolishly and improbably attempted to stigmatise the deep and careful deliberations of the Joint Commission as just another step in the liberal, ecumenist sell-out, preferring – for its own reasons – to re-open old wounds rather than pour out the healing balm of charity and truth. In accordance with the Bulletin’s declared policy of explaining our common understanding of the Orthodox faith, we published in this issue the key texts issued by the Joint Commission.
Members of the Joint Commission included official representatives of the Coptic Orthodox Church, the Syrian Orthodox Patriarchate of Antioch and All the East, the Supreme Catholicosate of All Armenians at Etchmiadzin, the Armenian Catholicosate of Cilicia, the Malankara Orthodox Syrian Church of the East and the Ethiopian Orthodox Church from the Oriental Orthodox family; the Ecumenical Patriarchate, the Greek Orthodox Patriarchate of Alexandria, the Greek Orthodox Patriarchate of Antioch, the Russian Patriarchate, the Romanian Patriarchate, the Serbian Patriarchate, the Bulgarian Patriarchate, the Georgian Patriarchate, the Church of Cyprus, the Church of Greece, the Church of Albania, the Czechoslovakian Orthodox Church, the Polish Orthodox Church and the Finnish Orthodox Church from the Byzantine Orthodox family.
First Agreed Statement (1989)
We have inherited from our fathers in Christ the one apostolic faith and tradition, though as Churches we have been separated from each other for centuries. As two families of Orthodox Churches long out of communion with each other we now pray and trust in God to restore that communion on the basis of the common apostolic faith of the undivided church of the first centuries which we confess in our common creed. What follows is a simple reverent statement of what we do believe on our way to restore communion between our two families of Orthodox Churches.
Throughout our discussions we have found our common ground in the formula of our common father, St. Cyril of Alexandria : mia physis hypostasis (he mia hypostasis) tou Theou Logou sesarkomene, and in the dictum that “it is sufficient for the confession of our true and irreproachable faith to say and to confess that the Holy Virgin is Theotokos” (Hom : 15, cf. Ep. 39).
Great indeed is the wonderful mystery of the Father, Son and Holy Spirit, one True God, one ousia in three hypostases or three prosopa. Blessed be the Name of the Lord our God, for ever and ever.
Great indeed is also the ineffable mystery of the Incarnation of our Lord Jesus Christ, for us and for our salvation.
The Logos, eternally consubstantial with the Father and the Holy Spirit in His Divinity, has in these last days, become incarnate of the Holy Spirit and Blessed Virgin Mary Theotokos, and thus became man, consubstantial with us in His humanity but without sin. He is true God and true Man at the same time, perfect in His Divinity, perfect in His humanity. Because the one she bore in her womb was at the same time fully God as well as fully human we call the Blessed Virgin Theotokos.
When we speak of the one composite (synthetos) hypostasis of our Lord Jesus Christ, we do not say that in Him a divine hypostasis and a human hypostasis came together. It is that the one eternal hypostasis of the Second Person of the Trinity has assumed our created human nature in that act uniting it with His own uncreated divine nature, to form an inseparably and unconfusedly united real divine-human being, the natures being distinguished from each other in contemplation (theoria) only.
The hypostasis of the Logos before the incarnation, even with His divine nature, is of course not composite. The same hypostasis, as distinct from nature, of the Incarnate Logos, is not composite either. The unique theandric person (prosopon) of Jesus Christ is one eternal hypostasis Who has assumed human nature by the Incarnation. So we call that hypostasis composite, on account of the natures which are united to form one composite unity. It is not the case that our Fathers used physis and hypostasis always interchangeably and confused the one with the other. The term hypostasis can be used to denote both the person as distinct from nature, and also the person with the nature, for a hypostasis never in fact exists without a nature.
It is the same hypostasis of the Second Person of the Trinity, eternally begotten from the Father Who in these last days became a human being and was born of the Blessed Virgin. This is the mystery of the hypostatic union we confess in humble adoration – the real union of the divine with the human, with all the 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 the willing and acting of Jesus Christ.
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.
The four adverbs used to qualify the mystery of the hypostatic union belong to our common tradition – without commingling (or confusion)
(asyngchytos), without change (atreptos), without separation (achoristos) and without division (adiairetos). Those among us who speak of two natures in Christ, do not thereby deny their inseparable, indivisible union; those among us who speak of one united divine-human nature in Christ do not thereby deny the continuing dynamic presence in Christ of the divine and the human, without change, without confusion.
Our mutual agreement is not limited to Christology, but encompasses the whole faith of the one undivided church of the early centuries. We are agreed also in our understanding of the Person and Work of God the Holy Spirit, Who proceeds from the Father alone, and is always adored with the Father and the Son. 
Second Agreed Statement (1990)
The first Agreed Statement on Christology adopted by the Joint Commission of the Theological Dialogue between the Orthodox and Oriental Orthodox Churches, at our historic meeting at the Anba Bishoy Monastery, Egypt, from 20th to 24th June 1989 forms the basis of this Second Agreed Statement on the following affirmations of our common faith and understanding, and recommendations on steps to be taken for the communion of our two families of Churches in Jesus Christ our Lord, Who prayed “that they all may be one”.
1. Both families agree in condemning the Eutychian heresy. Both families confess that the Logos, the Second Person of the Holy Trinity, only begotten of the Father before the ages and consubstantial with Him, was incarnate and was born from the Virgin Mary Theotokos; fully consubstantial with us, perfect man with soul, body and mind (nous); He was crucified, died, was buried, and rose from the dead on the third day, ascended to the Heavenly Father, where He sits on the right hand of the Father as Lord of all Creation. At Pentecost, by the coming of the Holy Spirit He manifested the Church as His Body. We look forward to His coming again in the fullness of His glory, according to the Scriptures.
2. Both families condemn the Nestorian heresy and the crypto-Nestorianism of Theodoret of Cyrus. They agree that it is not sufficient merely to say that Christ is consubstantial both with His Father and with us, by nature God and by nature man; it is necessary to affirm also that the Logos, Who is by nature God, became by nature Man, by His Incarnation in the fullness of time.
3. Both families agree that the Hypostasis of the Logos became composite (sunqetoj) by uniting to His divine uncreated nature with its natural will and energy, which He has in common with the Father and the Holy Spirit, created human nature, which He assumed at the Incarnation and made His own, with its natural will and energy.
4. Both families agree that the natures with their proper energies and wills are united hypostatically and naturally without confusion, without change, without division and without separation, and that they are distinguished in thought alone (th qewria monh). 20
5. Both families agree that He Who wills and acts is always the one Hypostasis of the Logos incarnate.
6. Both families agree in rejecting interpretations of Councils which do not fully agree with the Horos of the Third Ecumenical Council and the letter (433) of Cyril of Alexandria to John of Antioch.
7. The Orthodox agree that the Oriental Orthodox will continue to maintain their traditional Cyrillian terminology of “one nature of the incarnate Logos” (“mia fusij tou qeou Logou sesarkwmenh”), since they acknowledge the double consubstantiality of the Logos which Eutyches denied. The Orthodox also use this terminology. The Oriental Orthodox agree that the Orthodox are justified in their use of the two-natures formula, since they acknowledge that the distinction is “in thought alone” (th qewria monh). Cyril interpreted correctly this use in his letter to John of Antioch and his letters to Acacius of Melitene (PG 77, 184-201), to Eulogius (PG 77, 224-228) and to Succensus (PG 77, 228-245).
8. Both families accept the first three Ecumenical Councils, which form our common heritage. In relation to the four later Councils of the Orthodox Church, the Orthodox state that for them the above points 1-7 are the teachings also of the four later Councils of the Orthodox Church, while the Oriental Orthodox consider this statement of the Orthodox as their interpretation. With this understanding, the Oriental Orthodox respond to it positively.
In relation to the teaching of the Seventh Ecumenical Council of the Orthodox Church, the Oriental Orthodox agree that the theology and practice of the veneration of icons taught by that Council are in basic agreement with the teaching and practice of the Oriental Orthodox from ancient times, long before the convening of the Council, and that we have no disagreement in this regard.
9. In the light of our Agreed Statement on Christology as well as of the above common affirmations, we have now clearly understood that both families have always loyally maintained the same authentic Orthodox Christological faith, and the unbroken continuity of the apostolic tradition, though they have used Christological terms in different ways. It is this common faith and continuous loyalty to the Apostolic Tradition that should be the basis for our unity and communion.
10. Both families agree that all the anathemas and condemnations of the past which now divide us should be lifted by the Churches in order that the last obstacle to the full unity and communion of our two families can be removed by the grace and power of God. Both families agree that the lifting of anathemas and condemnations will be consummated on the basis that the Councils and Fathers previously anathematized or condemned are not heretical.”