The Chalcedonean Definition is the official Christology of the Catholic Church. It states that Christ is a single person with two natures: human and divine. These two natures are neither divided nor mixed.

The Oriental Orthodox Christological position is Miaphysitism. This states that Christ has a single nature, but that nature is both fully human and fully divine, with the human and divine elements being neither mixed with nor divided from each other.

Historically the Catholics have misunderstood miaphysitism as a form of monophysitism (Christ has a single nature which is either human or divine but not both) and the Oriental Orthodox have misunderstood Chalcedonean definition as being a form of Nestorianism (Christ was two persons).

In my analysis, both sides are going to great pains to ensure that Christ is fully human and fully divine. They both go about it in different ways, but both succeed in the goal, and so both are acceptable formulations

Recently the two sides have cooled off and the accusations of heresy against each other are not so strong. There have been moves by some to say that the dispute is just one of terminology, not substance. This includes joint statements signed by Pope Paul VI and Pope John Paul II, but despite this, the Catholic and Oriental orthodox Churches have not officially declared themselves in communion with each other, so I am not sure if Miaphysitism is considered an acceptable Christological position by the Catholic church.

Personally I find Miaphysitism to be more coherent and intuitive than the Chalcedonean 2 natures definition. As a Catholic, am I permitted to believe Miaphysitism so long as I don't simultaneously deny Chalcedon? And if it is permitted, then why aren't the Oriental Orthodox churches in full communion with the Catholic Churches as the Eastern Orthodox churches are?

Related question: is this what the Eastern Catholic churches that have an Oriental Orthodox background do? Ie. Accept that the Chalcedonean definition is Orthodox, but go ahead and teach Miaphysitism anyway? (I'm thinking of the Ethiopian, Eritrean and Coptic Catholic churches for example)

edit: I note that the wikipedia article for Miaphysitism says the following:

Historically, Chalcedonian Christians have considered Miaphysitism in general to be amenable to an orthodox interpretation, but they have nevertheless perceived the Christology of the Oriental Orthodox to be a form of Monophysitism (single nature doctrine).

This seems to indicate that Chalcedonians are able to accept Miaphysitism, given an appropriate interpretation.

  • "As a Catholic, am I permitted to believe Miaphysitism so long as I don't simultaneously deny Chalcedon?" Miaphysitism is a denial of Chalcedon by definition! That's the simple answer. Whether either Western or Eastern Catholics are required to be Chalcedonian is a question I don't know the answer to.
    – curiousdannii
    Commented Mar 28, 2017 at 5:14
  • The only reason i bother asking is because both positions have the same motivation: safeguarding the fact that Christ is fully human and fully divine. The question of whether christ has one nature or two natures seems far less important. Both positions succeed at safeguarding the humanity and the divinity and i think this was the whole point, the details are (potentially) incidental Commented Mar 28, 2017 at 5:28
  • I can imagine someone being a miaphysite and accepting chalcedon simultaneously if they are both taken as being orthodox christologies, even if they are inconsistent when placed next to each other Commented Mar 28, 2017 at 5:30
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    I feel like I should be offended that you say it sounds ignorant, but I'm not because you're right XD I don't actually know much about the details of either position, I'm only familiar with a surface level treatment. Generally when I'm doing theology I just assume the Chalcedonean definition as an axiom and miaphysitism appeals to me at face value Commented Mar 28, 2017 at 7:56
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    You might be interested in this Dialogue and Joint Declarations with the Roman Catholic Church from the Syriac Orthodox Church. There is also a description of miaphytism from an Eastern Orthodox perspective here.
    – guest37
    Commented Mar 28, 2017 at 13:17

2 Answers 2


The short answer is that, correctly understood, Miaphysitism can be compatible with the Catholic Faith.

In order to see how this is so, it is important to understand carefully what Catholics understand by “Miaphysistism.”

This position refers to a formula attributed to St. Cyril of Alexandria, intended to defend the so-called “communion of properties” in Christ:

μία φύσις τοῦ θεοῦ λόγου σεσαρκωμένη

one nature (physis) of the Word of God made flesh (sesarkomene)

(Briefly, the doctrine of the communion of properties, or communicatio idiomatum, means that the properties or actions of Jesus that proceed from his Divine Nature may rightly be ascribed to him as man, and vice versa. For example, we may rightly say both that God died on the Cross, and that Jesus the man created the universe. This communion arises because of the hypostatic union, since all actions are ultimately ascribed to the hypostasis, not the nature. See also Catechism of the Catholic Church [CCC] 466.)

It should be noted that St. Cyril (c. 376–444) made this formula before the Council of Chalcedon (451), and before the terminology carefully distinguishing “nature” (physis) and “Person” (hypostasis) had stabilized.*

Hence, if the term physis here corresponds roughly to the Chalcedonian concept of hypostasis, then this formula can certainly be interpreted in an orthodox manner.

The Magisterium, in fact, has solemnly affirmed that Cyril’s formula may still be used. In the Second Council of Constantinople, the following canon is found:

If someone confesses that a union of natures, divine and human, has taken place, or speaks of one incarnate human nature of the Word of God (μίαν πύσιν τοῦ Θεοῦ λόγου σεσαρκωμένην), but does not understand these formulations as in the teachings of the Holy Fathers, … let him be anathema” (Denzinger-Hünermann no. 429, my translation).

In referring to the “Holy Fathers,” the Council clearly means St. Cyril of Alexandria, who did not at all espouse a Eutychian or Apollinarian Monophysitism (both of which effectively deny the full humanity of Jesus).

If Miaphysitism is understood according to this precise formulation, then it is perfectly orthodox and sanctioned by the Magisterium (so long as we understand that the Council of Chalcedon used physis in a different manner).

Hence, one could say that the key difference between Miaphysitism (correctly understood) and Monophysitism is that, whereas the latter denies some aspect of Christ’s humanity, the former respects his full and perfect humanity.

* The terms physis and hypostasis come ultimately from Aristotle—although the Alexandrian fathers were highly influenced by Platonism—and, in philosophical terms, have roughly the same meaning. Therefore, exactly how these terms are employed in theology is conventional. Cyril was writing before physis came to signify that which answers the question “What is it?” and hypostasis came to signify the personal subject that answers the question “Who is it?”

  • Fascinating! +1 I guess a follow up question would be: do modern oriental orthodox Christians subscribe to the understanding of miaphysitism you outline in this answer? (In other words, is modern Oriental Orthodox Christology compatible with Catholicism?) Commented Mar 29, 2017 at 8:16
  • I'm on the edge of my seat, but I'm predicting I will be disappointed because I understand that the OO understanding of miaphysitism is "One nature (physis) from two natures", but not "One person (hypostasis) from two natures", which is what St Cyril seems to be saying, and so they may still fall foul of the Constantinopolitan anathema. Commented Mar 29, 2017 at 8:23
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    It sounds like the "Miaphysitism" which is permitted here is actually "Miahypostasisism", because "Physis" is understood as "hypostasis" in the St Cyril quote. Scratching my head Commented Mar 29, 2017 at 8:33
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    @TheIronKnuckle Naturally, any Oriental Orthodox Christian, or church, that wished to be in communion with the Church of Rome would need to accept the Council of Chalcedon, although they could keep using their Miaphysite formulation. I believe that is essentially what the Coptic, Ethiopic, and Armenian Catholics do. (Yes, each O.O. church has a small Catholic counterpart.) Commented Mar 29, 2017 at 9:01
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    @MikeBorden, yes with the communion of properties, we can say that God (the Son) died on the Cross. (But God the Father did not die on the Cross: that would be Patripassianism. Similarly, neither did the Holy Spirit.) Commented Jul 18, 2020 at 7:02

The OED defines "miaphysite" as:

Of or relating to the doctrine that in the person of Jesus there is either a single divine nature, or one inseparable nature, partly divine, and partly (subordinately) human

Both of these senses are heretical because Jesus doesn't have one nature (as also monophysites believe), nor does He have "one inseparable nature" that is "partly divine, and partly (subordinately) human." He has two natures that are each fully (not partly) human and divine.

The Council of Chalcedon (451 AD) condemned monophysitism and miaphysitism (μονο and μία both mean "one"):

Therefore, following the holy Fathers, we all teach that with one accord we confess one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and the same perfect in human nature, true God and true man, the same with a rational soul and a body, consubstantial with the Father according to divine nature, consubstantial with us according to the human nature, like unto us in all things except sin…

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    The definition of the OED isn't very good, since it defines "miaphysite" as either a monophysite or a miaphysite. The monophysites teach that Christ has a single nature, and it is divine. The miaphysites teach that Christ has a single nature, and it is both divine and human. The Chalcedonians teach that Christ has one person (hypostasis) and two natures, one divine and one human.
    – Wtrmute
    Commented Mar 28, 2017 at 16:37
  • @Wtrmute "The miaphysites teach that Christ has a single nature, and it is both divine and human._" That's one of the OED's definitions. It's heretical because it conglomerates the human and divine natures into one human-divine nature.
    – Geremia
    Commented Mar 28, 2017 at 19:33
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    I agree it is one of them; I argue it should be the only one, as the other definition is that of another group (the monophysites). As for whether it is heretic or not, I defer to the Holy Father's judgement on the matter.
    – Wtrmute
    Commented Mar 28, 2017 at 19:48
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    @Jeremiah This issue is slightly more complicated than it sounds. There is an orthodox sense in which Miaphysitism could be understood: one of the ecumenical councils (I believe it was Constantinople II—I will check in the Denzinger when I get a chance) specifically approves the formula attributed to St. Cyril of Alexandria, “one nature (physis) that has become flesh (sesarkomene)”, provided, of course, that the term physis takes on the meaning that Chalcedon gives to hypostasis. Commented Mar 28, 2017 at 20:58
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    @Jeremiah, I found it. See Denzinger-Hünermann no. 429: “If someone confesses that a union of natures, divine and human, has taken place, or speaks of one incarnate human nature of the Word of God (μίαν πύσιν τοῦ Θεοῦ λόγου σεσαρκωμένην), but does not understand these formulations as in the teachings of the Holy Fathers, … let him be anathema” (my translation). This is Constantinople II (553). The reason for the highlighted clause is specifically to allow the use of St. Cyril’s formula, provided it was understood correctly. Commented Mar 28, 2017 at 21:18

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