Catholicism & Orthodoxy: What is the Orthodox Church?

Two Families Called “Orthodox”

The word “Orthodox” means, in Greek, right belief — orthos (straight, correct) and doxa (belief, glory). It is a word every Catholic should recognize, because we used it first to describe ourselves. In the ancient creeds and councils, “orthodox” was simply the opposite of heresy. That both the Catholic Church and the Eastern churches use the term for themselves is not coincidence. It is a reminder that we are arguing over the same inheritance.

But when most people today say “the Orthodox Church,” they need to know they are pointing at one of two distinct Christian families that separated from Rome at different times, over different theological disputes, and that are not in full communion with each other.

This article focuses primarily on the Eastern Orthodox — the larger family, and the one whose separation from Rome is the direct subject of this series. The Oriental Orthodox receive their own treatment below, in the section on Chalcedon.

The Chalcedon Question: 451 AD

The first great fracture in the Christian East happened not with Rome but within the East itself, over a question that every Christian implicitly answers every time they pray: Who, exactly, is Jesus Christ?

The Council of Chalcedon (451) defined that Christ is one Person in two natures — fully divine and fully human — without confusion, without change, without division, without separation. This definition, ratified by Rome and eventually by Constantinople, was designed to steer between two errors: Nestorianism (which seemed to make Christ two persons) and Monophysitism (which collapsed the two natures into one).

The churches that became the Oriental Orthodox rejected this definition — not because they were Monophysites in the strict sense, but because they held to the formula of St. Cyril of Alexandria: one nature of the incarnate Word. They called themselves miaphysite (one united nature) and regarded the Chalcedonian two-natures formula as dangerously close to Nestorianism. The emperor, the patriarch of Constantinople, and Rome stood on one side; Egypt, Ethiopia, Armenia, and Syria on the other. The break was geographically clean and has lasted 1,573 years.

Autocephaly: No Head But Christ

If you want to understand Eastern Orthodoxy — what it is, and what it cannot do — you need to understand one word: autocephaly.

An autocephalous church (“self-headed”) is a church that governs itself independently. It elects its own patriarch or primate, issues its own canonical legislation, and is not subject to the jurisdiction of any other patriarchate. The Eastern Orthodox communion is not one church with a visible head. It is a fellowship of autocephalous churches, currently numbering fourteen that are universally recognized, plus several whose status is disputed.

At the center of this fellowship sits the Ecumenical Patriarch of Constantinople — currently His All-Holiness Bartholomew I. His title is primus inter pares: first among equals. He chairs pan-Orthodox gatherings, serves as a symbol of Orthodox unity, and enjoys a primacy of honor. What he does not possess is jurisdictional authority over other Orthodox churches. He cannot define doctrine for the whole communion. He cannot order the patriarch of Moscow or the patriarch of Antioch to do anything. His “primacy” is closer to that of a presiding officer than a chief executive. The Russian patriarch, who leads a church of perhaps 100 million faithful — roughly a third of all Eastern Orthodox — has never accepted even this much, and tensions between Moscow and Constantinople have defined modern Orthodoxy’s internal politics for decades.

Notice the paradox in the diagram above: the “first among equals” presides over a see of a few thousand faithful in a country that is 99% Muslim, while the patriarch of a rival see leads a hundred million. The moral and symbolic authority of Constantinople is immense. Its jurisdictional authority is nearly zero. This is the structural situation the Orthodox have lived with for centuries, and it matters enormously for the question of doctrinal unity — a question we will return to.

The Divine Liturgy

To understand the Orthodox, you must attend their liturgy. No description does it justice, but some preparation helps.

The standard Sunday liturgy is the Divine Liturgy of St. John Chrysostom, composed (in its essential structure) by the great Archbishop of Constantinople who died in 407. It is the same liturgy used in Antioch, in Moscow, in an Orthodox parish in Los Angeles, in a monastery on Mount Athos where monks have sung it without interruption for over a thousand years. Its antiquity is not ornamental. It is the point.

You enter through a nave facing an iconostasis — a screen or wall covered with icons, separating the nave from the sanctuary. The icons are not decorations. In Eastern theology, an icon is a window into heaven: the image, properly made and blessed, makes present the saint depicted. Veneration of an icon is not worship of wood and paint but honor directed through the image to the person it represents. The iconostasis itself is a theology: it places the faithful at the threshold between earth and heaven, the visible and the invisible, the time-bound and the eternal.

The congregation stands. Orthodoxy does not use pews in its traditional form (many modern American parishes have added them), but this is worth pausing on: the Western Church did not use them either, for most of its history. The nave of a medieval Catholic church was open floor — standing room, with perhaps stone ledges along the walls for the elderly and infirm. Fixed pews as standard furniture are largely a product of the Protestant Reformation, which moved the sermon to the center of worship and required seating for long catechetical preaching. Catholic churches adopted pews gradually in the post-Reformation centuries, partly under Protestant cultural influence, partly as the Counter-Reformation also placed new emphasis on preaching. The Orthodox never made that shift. In retaining the standing posture, they preserve what is actually the older Christian universal: you stand because Sunday is the day of the Resurrection, and you do not kneel before a risen King.

The chanting you hear throughout — that sound that can seem so foreign to Western ears — is the Byzantine musical tradition, shaped by the same modal scales that gave Western Gregorian chant its particular gravity. The resemblance to certain Middle Eastern musical forms is not coincidence and not borrowing: both Byzantine chant and Islamic music grew from the same ancient Mediterranean musical soil. But Byzantine chant was already fully formed, already ancient, already sung in the liturgy of the Hagia Sophia, before the first Muslim prayer was ever called. You are hearing an original, not a derivative.

Eastern Theology: Theosis and the Living God

Every tradition in the Church has a center of gravity — a core insight around which everything else organizes. For the Latin West, shaped by Augustine and Aquinas, that center has often been justification: how the sinner is made righteous before God. For the Christian East, the center is theosis: how the human person is transformed into a sharer in the divine nature.

The scriptural foundation is 2 Peter 1:4: the promise that through Christ we may “become partakers of the divine nature.” The theological tradition that developed from this verse in the East is not a minor piety. It is the organizing principle of Eastern soteriology, anthropology, and ascetical life. Salvation, in the Eastern view, is not primarily forensic — a legal verdict of acquittal — but ontological: a real participation in the life of God. St. Athanasius gave this its most famous formulation: “God became man so that man might become God.” St. Maximus the Confessor spent his life elaborating what this means. The entire tradition of Eastern monasticism — from the Desert Fathers through Mount Athos to today — is ordered toward it.

This is not foreign to Catholic theology. The same truth is present in Thomas Aquinas, in the mystical tradition of Meister Eckhart and John of the Cross. But the emphasis differs. The East keeps theosis at the center; the West tends to treat it as a pinnacle of mystical experience available to the few. In the East, it is the ordinary destiny of every baptized Christian.

Two other features of Eastern theological style deserve mention. First, the apophatic tradition (from apophasis, negation): the insistence that God ultimately exceeds every concept, every category, every affirmation. We can say what God is not more reliably than what He is. Pseudo-Dionysius the Areopagite, John of Damascus, and Gregory of Nyssa are the great Eastern masters of this tradition. It does not mean agnosticism. It means that silence before the Holy Trinity is a form of theology, not its absence.

Second, the East has produced a tradition of prayer — the Hesychast tradition — centered on the constant interior repetition of the Jesus Prayer: Lord Jesus Christ, Son of God, have mercy on me, a sinner. The Philokalia, an anthology of Eastern spiritual writing compiled in the eighteenth century, is one of the most important spiritual texts in the Christian tradition, Catholic or otherwise. The anonymous Russian classic The Way of a Pilgrim brought this tradition to the West in the nineteenth century and has never gone out of print. These are not peripheral curiosities. They are the lived fruit of a theology that takes theosis seriously as the destiny of ordinary Christians.

What They Have: A Catholic Assessment

The Catholic Church does not speak of the Orthodox the way she speaks of Protestant communities. The language is different because the reality is different.

The Second Vatican Council’s Unitatis Redintegratio (1964), §15, is unambiguous: the separated Eastern Churches “possess true sacraments, above all — by apostolic succession — the priesthood and the Eucharist, whereby they are still joined to us in closest intimacy.” The Catechism of the Catholic Church §838 describes the Orthodox communion as one where the faith “is so profound that it lacks little to attain the fullness that would permit a common celebration of the Lord’s Eucharist.” The Congregation for the Doctrine of the Faith’s 2000 declaration Dominus Iesus formally classifies the Orthodox as true particular Churches — the same theological category as Catholic dioceses — distinguishing them explicitly from Protestant “ecclesial communities.”

What this means concretely: an Orthodox priest stands in genuine apostolic succession. His ordination is valid. His absolution is valid. The Eucharist he consecrates is the Body and Blood of Christ. His parishioners are genuinely baptized. When they die having loved God and neighbor, the Catholic Church does not presume to know their fate — and the saints canonized in the Orthodox tradition, whatever the ecclesiological complications, were real saints whose holiness was real.

What They Lack: The Structural Problem

Having said all of the above generously and truthfully, the Catholic must now say something equally honest: the Orthodox Church, for all its genuine sanctity, genuine sacraments, and genuine apostolic succession, has a structural problem that no amount of goodwill can resolve from within.

It has no universal teaching authority.

In the Catholic Church, when a question of faith or morals requires a definitive answer, there is a mechanism: the Pope, speaking with the bishops in council or alone under the conditions defined at Vatican I, can define a matter for the whole Church, binding on all the faithful. This has happened rarely and carefully. But the mechanism exists. It has produced the defined dogmas of the Immaculate Conception, the Assumption, and the precise formulations of Christology that the whole Church holds without variation from Nigeria to the Philippines to San Antonio.

In the Orthodox Church, no such mechanism exists. An ecumenical council of the whole Church is theoretically the highest authority — but the Orthodox have not held one they all recognize since Nicaea II in 787. The patriarchs cannot compel each other. The Ecumenical Patriarch cannot bind the Russian patriarch. The Russian patriarch cannot bind the Greek patriarch. When individual churches disagree — as they increasingly do — there is no court of appeal, no binding arbiter, no Peter.

The result is what you would expect: drift. Not collapse — the Orthodox have maintained the ancient faith with remarkable fidelity in many areas. But drift. The Orthodox Church in America has at times taken pastoral positions on remarriage, ecumenism, and sexual ethics that differ from Greek practice, which differs from Russian practice. There is no mechanism to adjudicate. The ancient faith is preserved by inertia and tradition, which are powerful forces. But inertia and tradition, without a living teaching authority to interpret and apply them, are not the same as the guarantee Christ gave Peter.

The 2016 Council: A Live Demonstration

In June 2016, on the island of Crete, the Orthodox Church held what it called the Holy and Great Council — the first pan-Orthodox gathering in over a thousand years. It had been in preparation for fifty years. Patriarch Bartholomew of Constantinople called it a historic moment for Orthodox unity.

Four of the fourteen autocephalous churches refused to attend. The Russian Orthodox Church — the largest Orthodox body in the world — withdrew at the last moment, citing procedural objections. The Georgian, Serbian, and Bulgarian churches followed. The Antiochian church had already declined to participate, citing a separate dispute with the Patriarchate of Jerusalem over jurisdiction in Qatar.

The council met anyway, with ten churches present. It produced documents on the Orthodox diaspora, fasting, the sacrament of marriage, and relations with non-Orthodox Christians. When the non-attending churches received the council’s documents, several issued rejections. The Russian church objected to language in the document on ecumenism. The Georgian church rejected several documents outright.

They Left: Said Charitably, Said Clearly

The Catholic Church does not teach that the Orthodox are strangers to Christ, or that their sacraments are empty, or that their saints are frauds. She teaches the opposite of all of these things. But she also holds — without apology, without qualification — that she is the Church Christ founded, that the visible unity of the Church around the successor of Peter is not optional, and that the Eastern churches’ separation from that unity is a wound: not something to be celebrated, not something that simply “happened,” but a departure.

It was not a departure that happened all at once, and it was not a departure for which the Catholic side bears no responsibility. Foundation Article I examined that record honestly. The jurisdictional overreach of Nicholas I, the catastrophe of 1204, the Latinization abuses, the bungled legation of Humbert of Silva Candida — these are real failures, named and owned. But owning our failures does not change the direction of the separation. The councils that formally repudiated Florence (1484) were Eastern synods making Eastern choices. The patriarchs who closed their doors to Roman communion were Eastern patriarchs closing Eastern doors.

The Catholic Church has never closed hers.

The invitation that Paul VI extended to Athenagoras in Jerusalem in 1964 — the first embrace of pope and patriarch in 525 years — was not a diplomatic gesture. It was a statement of what the Catholic Church has always believed: that the Eastern churches belong in the house, that their liturgical traditions are treasures of the whole Church, that their theological heritage is not a competitor to Latin theology but its complementary lung, and that the path to full communion does not require them to become Latin.

Come Home

The Orthodox Christian who kneels before an icon of the Theotokos, who stands through two hours of the Divine Liturgy, who reads the Philokalia in the small hours of the morning and strains toward theosis — that person is not a stranger to the Catholic. They are a brother, a sister, someone whose faith shares the same Apostles, the same Fathers, the same Creed, the same Eucharist. The distance between us is not the distance between Christianity and something else. It is the distance between two rooms in what was once one house.

The Catholic claim is not that the Orthodox have nothing. It is that they have almost everything, and that the “almost” matters — not as a technicality but as the visible unity for which Christ prayed on the night He was betrayed, the unity that was meant to be the Church’s witness to the world that the Father had sent the Son. A divided Christianity cannot make that witness. A Christianity that cannot hold its own council is a Christianity answering hard questions with silence when the world needs a voice.

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