The 3rd Ecumenical Council of 431 AD dogmatically defined the orthodox position, against the Nestorian heresy, that Jesus was one person with both a human and a Divine nature, not two persons (a merely human Jesus possessed of the separate Divine Christ), as in the classically defined “Nestorian heretical” interpretation of the Bible. Shortly afterwards the Monophysite (“one nature”) heretical interpretation of the Bible became popular in the Church, a too-extreme reaction to Nestorianism promoted most strenuously by the otherwise pious monk Eutyches, agreeing that Jesus was initially one person with both a human and a Divine nature, but arguing that Jesus’ finite human nature was immediately absorbed into His infinite Divine nature, leaving Jesus with one nature only, the Divine, no longer truly nor ultimately human at all (many proponents of this theory had followed to its most extreme possible conclusions the most extreme anti-Nestorian formulations of Saint Cyril of Alexandria, who had been the champion of orthodoxy against the Nestorian heretics, deputized by Pope Celestine to preside over the 3rd Ecumenical Council which had condemned Nestorianism – but unfortunately because of these potential long-term conclusions his most extreme formulations were not adopted by the 3rd Ecumenical Council, even though the Catholic Church would later call Saint Cyril a “Doctor” [Latin for “Teacher”] of the Church for his work against the Nestorian heresy). The too-extreme, reactionary Monophysite interpretation of Saint Cyril’s more extreme formulations, especially as articulated by the monk Eutyches, violated what had already been established earlier within the Church by “the Cappodocian Fathers” – Saint Basil the Great, Saint Gregory of Nazianzen (“the Theologian”) and Saint Gregory of Nyssa, the greatest defenders of the Trinity whose Trinitarian doctrine was victorious at the 2nd Ecumenical Council of 381 AD against the Arian and Eunomian heretics. The Cappadocians had also articulated clearly the Church’s long-implicit traditional faith that “what Christ did not assume, He did not redeem” – therefore Jesus needed to have a truly and fully human nature, as well as a divine nature, to redeem us humans at all. The proponents of the heretical Eutychian Monophysite interpretation of the Bible were so determined that when a 4th Ecumenical Council was called to settle the controversy in 449 AD, they stacked the Council with Monophysites, bullied the orthodox representatives, and refused to allow Pope Saint Leo the Great’s famous Decree of Leo to be read. This 449 Council then declared the Eutychian Monophysite heresy to be the true form of Christianity! Pope Saint Leo the Great declared the 449 Council null and void, a “robber” council, which necessitated another Council be called to replace it, held in 451 AD at Chalcedon, and Leo (against the tendencies of those inclined to to compromise with the Eutychian, Mononphysite heretics) directed it to adopt his Decree of Leo which brilliantly articulated and explained the previously more implicit orthodox faith of the Christian Church, clarifying just why Monophysite Christianity was heretical, because it violated the fundamental Christian truth (in the Bible but not explicitly) which Leo had at last clearly articulated and explained: that Jesus Christ is one person in two natures, Divine and human, that exist in Jesus Christ without confusion or change (versus the Monophysite heresy), without division or separation (versus the Nestorian heresy), such that Jesus is consubstantial (of the same substance) with the Father with respect to His Divinity, and consubstantial with us with respect to his humanity. In other words, Jesus Christ was not just one person who was both Divine and human, as the 3rd Ecumenical Council had dogmatically proclaimed against the Nestorian heretics within the Church, but Jesus Christ was and remained fully Divine and fully human, which is the standard mature explicit expression of (originally more implicit) orthodox, Apostolic Christianity to this day, still shared in common by the (Eastern and Western) Catholic, Eastern Orthodox, and most (Western) Protestant Churches, but not necessarily throughout history by the “Lesser Eastern Churches” (nor by the now “doctrinally liberal” arms of the historic, mainline Protestant churches, which, as a result of Protestantism’s denial of the Holy-Spirit-guided Living Sacred Tradition (handing-on) of the Christian faith from generation to generation, have divorced themselves from traditional Christian orthodoxy (“right teaching”) and called into question virtually every element of historic Christianity, including the Canon of the Bible itself).
Nestorianism and Monophysitism were and are major Christological heresies, but it must be noted in their defence that it was for a variety of NON-THEOLOGICAL reasons like language barrier (not speaking either Greek or Latin, the languages in which the Ecumenical Councils were held), political and cultural barriers, isolation from the Roman Empire where the Councils were held, or being at war with the Persians and so not even participating in the Council that the various “Lesser Eastern Churches” at the time of the 3rd and 4th Ecumenical (worldwide) Councils of the Universal (Catholic) Christian Church refused to condemn these heresies and thus (unfortunately) also schismatically refused to remain in the fellowship of their Catholic Patriarchs who had participated in the Councils and thus they refused to stay within the Catholic (Universal) Communion of Orthodox Christian Sister Churches of the First Millennium. Portions of these Churches later recanted their association with Christological error, later “received” the Council of Chalcedon and returned to the Catholic (Universal) Christian Communion in later centuries and remain faithful Eastern (non-Roman) Rite Catholic Christians to this day (such as the Chaldean Catholic Church, which formerly included Nestorians, and the Armenian Catholic Church, formerly Monophysite).
It is also very much worth noting that there is a very real potential for eventual (even soon) reunification with what remains of those ancient “Lesser Eastern Churches” (now often called “Pre-Chalcedonian” Churches) who at the time did not accept the 451 AD 4th Ecumenical Council of Chalcedon’s dogmatic definition of Jesus as “fully God and fully man” and so did not remain in the ancient Catholic Communion of Orthodox Christian Sister Churches of East and West which was the great majority of Christians then and still the majority now, all of whose descendent Christians today, (Eastern and Western) Catholic, Eastern Orthodox, and most (Western) Protestant, remain united in this mature Chalcedonian Christologicial fundamental definition of Christian faith).
This reunification would be based on fact that it can now be shown that in some cases mere political concerns [1, see below for details] or language and culture barrier issues clouded the issue so that sometimes the “Lesser Eastern Churches” were not embracing the Nestorian and Monophysite heresies, but were simply not yet prepared to anathematize (condemn) these new heretical positions they did not fully understand, not yet compelled by new, more precise dogma from the Councils they did not fully understand. In some cases they were simply more comfortable maintaining the previous, less developed Christology of the time which remained open to the heretical interpretations without promoting them.
Now, this did result in some of the “Lesser Eastern Churches” becoming a haven for genuine Nestorian and Monophysite heretics, unwelcome in the majority territories of the strongly-tied Catholic Communion of Christian East and West (mainly located in the still-standing [though not for long] Roman Empire of East and West), to flock to in order to practice their heretical form of Christianity. But still, it was often not the case that a “Lesser Eastern Church” (“Pre-Chalcedonian Church”) embraced or promoted the heresy but only accepted it among some of their members because their theology of Christ (Christology) had not yet developed sufficiently to the point, as it did in the more mature theology of the 3rd And 4th Ecumenical Councils recognized by the great majority of Christians, that these heresies could be clearly seen as heresies, ultimately incompatible with the orthodox Christian faith as passed on in the Christian Tradition at least implicitly since Apostolic times.
In the centuries since, the minority “Lesser Eastern Churches” of today (The Assyrian Church of the East and the Oriental Orthodox Family of Churches descended from the ancient Antiochian and Alexandrian Patriarchates of the Catholic Church) have developed their Christology along orthodox lines and would now better understand the 431 and 451 AD Councils’ objections, so they would and have in fact now clearly condemned classically-understood heretical Nestorianism and Monophysitism, in the formal dialogues between these (Pre-Chalcedonian) Churches and the (Chalcedonian) Catholic and Orthodox Communions of Churches which together still represent the great majority of the world’s Christians. For the most part the Pre-Chalcedonian Churches now interpret Nestorian or Monophysite formulas, if still in use, in ways acceptable to the highly developed theology and dogma of the Orthodox and Catholic (Universal Christian) Church Communion.
Thus if any of the Pre-Chalcedonian “Lesser Eastern Churches” (traditionally so-called by size comparison to the far larger Chalcedonian Eastern Orthodox Church, but calling themselves the Assyrian Church of the East and the Oriental Orthodox Family of Churches) are no longer committed to nor even open to the possibility of these long-condemned heresies, but are now prepared to likewise condemn them, as they have in Statements of jointly-agreed Christology with Catholic popes, even if they might reasonably claim to never have actually held the heresies but were victims of misunderstandings and confusion (tools which Satan regularly uses to keep Christ’s Church divided), and even if they still use some formulas used by the ancient heretics but now formally interpret them in ways compatible with orthodox Christianity, and willingly renounce all truly heretical interpretation of these formulas, and desire reunification within the much larger Catholic Church Communion they left which they can add to within its unity in diversity; if these conditions are met there should be no remaining barrier to their full reunification with today’s enduring Catholic Communion of (currently 26) Orthodox Christian Rites or Sister Churches of East and West, as other formerly Nestorian or Monophysite Churches have already reunified (for example the Chaldean Rite of the Catholic Church and the Syro-Malankara Catholic Church).
In fact, the “Pre-Chalcedonian” (and “Pre-Ephesian” – before the Council of Ephesus) Assyrian Church of the East, one of the oldest of Christian Churches before losing Catholic Communion by becoming associated with Nestorianism, and once very large outside of the borders of the Roman and Byzantine (Eastern Roman) Empires but now a very small, persecuted minority in Muslim territories, seems to be on a “fast track” to restoring the Church communion lost so long ago. Their schism is more due to distance and lack of contact with the Roman Empire where the dispute and the Council called to settle it took place, than to any obstinate embracing of Nestorianism for theological reasons against those of the Council. Thus the 1994 Common Christological Declaration Between the Catholic Church and the Assyrian Church of the East, written jointly by Blessed (soon to be canonized) Pope John Paul II and Catholicos-Patriarch Mar Dinkha IV, the Heads of their respective Churches, established essential Chalcedonian equivalency in current Christology, and the 1997 Joint Synodal Decree for Promoting Unity – Between the Assyrian Church of the East and the Chaldean Catholic Church began an era of close mutual cooperation between the Assyrian Church and the Chaldean Catholic Church – former Assyrians who are already in full communion with the Catholic Church, maintaining their distinct Assyrian cultural expressions of Christianity but with fully Chalcedonian, Orthodox, Catholic Christology. These two Churches already share traditional territory and rituals, and witness for Jesus Christ even to the shedding of their blood in a hostile, anti-Christian environment, and this push for unity helps them to do it better together.
The Oriental Orthodox Family of Churches, which include the majority of Christians today in Egypt and Syria, who were long associated with the Monophysite heresy but today preferring the term “Miaphysite” based on a term used by Saint Cyril of Alexandria against the Nestorian heretics, and one more open to orthodox interpretation, in 2004 entered into annual formal theological dialogue with the Catholic Church Communion and in 2009 the International Joint Commission for Theological Dialogue Between the Catholic Church and the Oriental Orthodox Churches produced a very significant Joint Document entitled Nature, Constitution, and Mission of the Church which firmly established tremendous common ground and mutually rejected Eutychian Monophysitism, although the full Christological subleties in the different approaches will likely take longer to thoroughly sort out [2, see below]. A complete equivalency of current (Pre-Chalcedonian) Oriental Orthodox, Miaphysite Christology with the classic Chalcedonian, Catholic (Universal) Christology recognized by the vast majority of Christians as the standard of Christian orthodoxy has not quite yet been firmly established, but it is likely that the two approaches are on a trajectory of convergence with each other and with further dialogue conducted in a patient and loving manner (because of Christ and His desire His followers be one), a common precise formula or definition fully acceptable to both sides can eventually be found, so as to completely remove the biggest barrier to communion with each other. This kind of dialogue over controversial theological issues is in fact how the Early Ecumenical Councils came to establish the Christological (and other) dogmas in the first place – talking to each other helped both sides of the dispute to further clarify and define their own position until both sides could see that they were talking about the same thing, now understood better, as they were trying to doctrinally express their common personal experience of Jesus Christ. Thus there is great reason for hope that despite their past association with the heresy of Monophysitism and failure to “receive” the Council of Chalcedon, which separated them (as “schismatics”) from the ancient Catholic Church Communion in the 5th Century, the Oriental Orthodox Churches can, after further dialogue, be once again reunified with the Catholic Church, adding to its already rich unity in diversity amongst 26 different Rites sharing common faith, and further strengthening it by their courageous and powerful witness to the love and joy of Jesus Christ throughout so many centuries of persecution in Muslim territories. This eventual reunion seems very possible as in only the first 5 years of formal dialogue (2004-2009) these two Church Communions have already built a strong foundation together towards reunion, because the dialogue is based on what was learned in the previous (and continuing) Catholic Church\Eastern Orthodox Church dialogue over decades, which has also made much progress already towards healing the First “Great Schism” of Christianity that was a “pure” schism, without any association with heresy[3, see below]. See The First Great Schism of Christianity and its Precedent in Division and in Healing.
© 2011 Peter William John Baptiste, SFO
Go To The Papacy’s Solid Foundation in Undivided Early Church History Since Apostolic Times: The Papacy’s Long and Wide Acceptance in the East Before the 2nd Millennium Schism of the Largest Portions of the Eastern Orthodox and Catholic Churches from the Catholic (Universal) Christian Communion of Orthodox Eastern and Western Catholic Sister Churches Collectively known as the Catholic Church
 Merely political and historical factors involved in the “Lesser Eastern Churches” non-acceptance of Chalcedon’s newly-defined orthodoxy included things like the fact that the Armenian Christians were too busy fighting the Persians at the time and so did not even participate in the Council. Yet today (and for centuries) there have been reunified Armenian Catholics who repudiated their past association with a Christological heresy (an association coming about perhaps only because Armenians initially were not involved in the resolution of the Monophysite controversy). In fact, so faithful to the orthodox and Catholic faith are they that the Armenian Catholic Patriarch Gregory Peter Cardinal Agagianian was considered a frontrunner among the Cardinals to be elected pope of the Catholic Church in the 1958 Conclave (which elected Pope John XXIII instead). Other political factors included the fact that the Byzantine (Eastern Roman) Empire was militarily oppressive in its (otherwise laudable) insistence that the 4th Ecumenical Council be accepted by those who were not quick to “receive” the Council in Egypt, again partially due to language and culture barrier reasons, and this military oppression simply made them “dig in their heels” for the faith as they still understood it, whereas in a loving Christian dialogue context (as today’s fruitful dialogues between Chalcedonian orthodox and “Pre-Chalcedonian” Churches), without such non-theological factors, an agreement and restoration of full unity might have been possible still in the First Millennium.
 An earlier, but rushed, not near as thorough dialogue, between the (Pre-Chalcedonian) Oriental Orthodox Churches and the (Chalcedonian) Eastern Orthodox Church Communion, much too hastily declared full equivalency of faith and therefore intention to embark upon full Church reunion, which went nowhere as the remaining discrepancy in subtleties of Christological understanding gradually became apparent, and also because the hurried dialogue had started with the biggest area of difference, in Christology, and quickly declared equivalency without truly journeying together and discovering each other’s similarities, the compatibility of the entirety of each other’s Christian beliefs, getting to really know each other and to coming to really desire full communion with each other. This recent Oriental Orthodox/Catholic Church dialogue is instead based on the much superior model of the Catholic Church/Eastern Orthodox Church dialogue, which, starting from commonalities and taking its time over decades, has much more firmly established a solid basis for reunion so far, even though its long process is not yet finished. See The First Great Schism of Christianity and its Precedent in Division and in Healing.
 At the Institute for Promoting the Gift of Truth, we speak (in union with the common conception) of the Undivided Early Church of the First Millennium before 1054, because the First “Great Schism” of this Church, resulting in the separated Catholic and Eastern Orthodox Church Communions, happened in 1054 (though only complete and total with Muslim interference after the Muslim conquest of Constantinople in 1453), and we do not count the very many earlier, smaller schisms wherein smaller groups of Christians were separated from this Undivided Early Church because of heresies. In this sense the 1054 Schism is the “First,” the first enduring “pure” Schism, without any trace of heresy, even though there were earlier schisms such as those which are the subject of this page, associated with the Nestorian and Monophysite heresies. Still, the two 5th Century schisms which resulted in the separated Assyrian Church of the East and the Oriental Orthodox Family of Churches deserve to be in a different (and superior) category than the majority of the many earlier, smaller schisms associated with heresy, because unlike all the others they have endured to the present day; they do not deny the Divinity of Christ like so many of the others did; at the time of the schisms they involved a far larger portion of Christians (much of the ancient Antiochian and Alexandrian patriarchates, before both the “Pre-Chalcedonian” and “Chalcedonian” portions were devastated by Islam); and, as described above, there is good evidence they did not fail to receive the faith as defined at Chalcedon simply due to the obstinate embracing of a heresy after the Church had ruled against it, like so many of the heretics whose churches did not endure, but a great many non-theological factors like language and cultural barriers and military oppression interfered with their reception of Chalcedon, and so “Chalcedonian” Christians must be patient and understanding in our dialogue with them, helping them to see what the bulk of the Church saw in the 5th Century that they missed out on, but likely also further refining and better understanding our own Chalcedonian position, thus all the better coming to understand Christ our Lord and God ourselves, through our dialogue with them for love of Christ and world He loves which needs to see Him in our Christian “love for one another.”