Introduction
Eastern Orthodox theologians often distance themselves from “Miaphysite” Christology, associating it with the heresy of Eutyches or viewing it as an Oriental Orthodox error. Yet their own councils—especially the Third Ecumenical Council (Ephesus I, 431) and the Fifth Ecumenical Council (Constantinople II, 553)—have already affirmed the core of Miaphysite Christology as Orthodox. To be truly Eastern Orthodox is to affirm Miaphysite Christology in its Cyrilline form. The irony is that what most Eastern Orthodox today regard as heterodox or even “heretical” was officially proclaimed as Orthodoxy by their own Church.
1. Ephesus I: Miaphysite at the Root
Before turning to Chalcedon, consider the Third Ecumenical Council—Ephesus I (431), which Eastern Orthodoxy fully accepts. It explicitly endorsed St. Cyril’s Third Letter to Nestorius and his Twelve Anathemas, both of which uphold the Miaphysite formulation: “one incarnate nature of God the Word” (μία φύσις τοῦ θεοῦ λόγου σεσαρκωμένη). In affirming Ephesus I, Eastern Orthodoxy has already committed itself to Miaphysite Christological language and theology. There is no way around this.
2. Chalcedon’s Contradictions
The Council of Chalcedon (451) claimed fidelity to Cyril, but its actions tell another story:
- It refused to read Cyril’s Third Letter to Nestorius, which contains Cyril’s Miaphysite formula.
- It ignored the Twelve Anathemas, Cyril’s primary tool against Nestorius.
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It readmitted Theodoret of Cyrus and Ibas of Edessa—both had condemned Cyril’s 12 Anathemas—without requiring any retraction of their anti-Cyrilline theology.
- It introduced Dyophysite Christology as the new standard, without affirming—as the Fifth Council later would—that both Miaphysite and Dyophysite expressions can be Orthodox when rightly understood.
This reveals a contradiction: Eastern Orthodoxy affirms Ephesus I and its Miaphysite language, while Chalcedon pivoted to a different theological framework. It claimed to uphold Cyril and Ephesus I but did so while advancing terminology and expressions those sources never used, without at least affirming both.
What Chalcedon truly upheld was the Formula of Reunion, drafted by Theodoret and reluctantly approved by Cyril for the sake of unity. This formula neither used “one incarnate nature” nor the Dyophisite formula “in two natures.” Thus, the Chalcedonian phrase “in two natures” was foreign not only to Ephesus I but even to the compromise formula it leaned on. In doing so, Chalcedon alienated all the Churches that adhered to the Miaphysite Christological formula of Cyril and Ephesus I, precipitating the schism of 451 AD.
This historical and theological background is essential for understanding why the Fifth Council’s affirmation of Miaphysite expression was not an anomaly—but a restoration of Eastern Orthodoxy’s original Christological voice.
3. Constantinople II: Restoring Cyril’s Language and the Orthodox faith of Ephesus I
A century later, the Fifth Ecumenical Council (553) corrected course:
- It reaffirmed Cyril’s Third Letter and Twelve Anathemas.
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It anathematized Theodoret’s and Ibas’s anti-Cyrilline writings.
- It stated that both expressions—“in two natures” (Antiochene) and “one incarnate nature” (Alexandrian)—are Orthodox if rightly understood.
Canon 7 affirms the Dyophysite expression (“in two natures”):
“If anyone, when speaking of the one Christ, uses the expression ‘in two natures,’ …to divide or separate the natures, introducing two Christs or two Sons—let him be anathema.”
Canon 8 affirms Miaphysite Christology:
“If anyone uses the expression ‘from two natures’ or ‘one nature of God the Word made flesh,’ and does not understand those expressions as the holy Fathers have taught—to wit, that of the divine and human nature there was made a hypostatic union, whereof is one Christ—but from these expressions tries to introduce one nature or substance [made by a mixture] of the Godhead and manhood of Christ, let him be anathema.”
Both expressions in Canon 8 are drawn directly from St. Cyril and are fully accepted within Miaphysite Christology. These expressions are treated as equally Orthodox, grounded in the patristic tradition and acknowledged by the Council as valid formulations. Eastern Orthodox who reject Miaphysite expressions are dismissing expressions that their own Council explicitly affirmed and protected. The condemnation of Eutychianism is irrelevant to Miaphysitism, which also rejects any confusion, mingling, or separation of the natures.
Though the Dyophysite expression remains the default expression within Eastern Orthodoxy, some argue its adoption is required because Chalcedon was never nullified. However, Constantinople II did not abolish Chalcedon—it re-Cyrillized it, giving full legitimacy to Miaphysite expression without exclusively requiring Dyophysite terminology.
4. What Miaphysitism Actually Teaches
Miaphysitism, as articulated by St. Cyril and maintained by the Oriental Orthodox:
- Affirms that Christ is fully God and fully man.
- Teaches the distinction of the natures remains real after the union, but is spoken of only in contemplation (theoria).
- Refuses to speak of Christ as if He were two subjects or agents acting separately.
This is exactly what the Fifth Council affirmed. There is no theological deviation—only terminological variation.
5. The Modern Eastern Orthodox Dilemma
Despite accepting the Fifth Council, many modern Eastern Orthodox:
- Deny that Miaphysitism is Orthodox.
- Remain unaware of the council’s affirmations.
- Reinterpret Canon 8 as requiring Dyophysite language alongside Cyrilline phrasing—a demand the canon never makes.
This leads to an untenable position: accepting a council that affirms Cyrilline Miaphysitism while denying Miaphysitism in practice. Although Constantinople II did not abolish Chalcedon, it re-Cyrillized it, giving full legitimacy to Miaphysite expression without requiring Dyophysite expression alongside. Dyophysitism remains the default expression within Eastern Orthodoxy, but Constantinople II recognized both expressions as Orthodox when understood correctly.
Conclusion
The Eastern Orthodox Church, through its own ecumenical councils, has already affirmed Miaphysite Christology—not as a tolerated variant, but as an authoritative expression of the faith. The Third and Fifth Councils enshrined the very formula that Chalcedon sidestepped: “one incarnate nature of God the Word.” To reject Miaphysite Christology today is to abandon Orthodox tradition. What many now label as heretical was, in fact, once proclaimed as the faith of the Eastern Orthodox Church. To be truly Eastern Orthodox is to affirm the faith of one’s own councils—namely Ephesus I and Constantinople II—not merely in name, but by embracing the very formulas and canons they upheld.