What Does the Church Say About the Orthodox?

The heart of Catholic teaching on the Orthodox is contained in a statement of the Catechism of the Catholic Church that deserves to be quoted in full, because it is today the official reference formulation:

"With the Orthodox Churches, this communion is so profound that it lacks little to attain the fullness that would permit a common celebration of the Lord's Eucharist." — Catechism of the Catholic Church, §838^[4]

Everything is in these few words. On the one hand, the Church does not say that communion is broken: she says it is real. On the other, she does not say it is complete: it lacks "little," but that little is decisive, since it still prevents eucharistic concelebration. Catholic teaching on the Orthodox therefore always unfolds in this twofold register: acknowledging everything that is already there, honestly naming what is still missing. That is exactly what we shall now detail.

The first question, and the weightiest in its consequences, is that of ecclesial status. The Catholic Church does not reserve the word "Church," in the strong theological sense, to herself alone: she also grants it, by full right, to the Orthodox Churches.

"True Particular Churches": The Formula of Dominus Iesus

In 2000, the Congregation for the Doctrine of the Faith, then headed by Cardinal Joseph Ratzinger, published the declaration Dominus Iesus, which clarifies ecclesiological vocabulary with particular sharpness:

"The Churches which, while not existing in perfect communion with the Catholic Church, remain united to her by means of the closest bonds, that is, by apostolic succession and a valid Eucharist, are true particular Churches." — Congregation for the Doctrine of the Faith, Dominus Iesus, §17^[5]

The word "true" is technically precise here: it means that the Church of Christ is present and operative in these Churches^[6]. An Orthodox community is therefore not a mere gathering of sincere believers: it is a particular Church in the full sense, endowed with bishops, priests, sacraments and a fully valid liturgical life. This recognition is not a diplomatic compliment: it is a doctrinal judgment.

True Sacraments and a Valid Apostolic Succession

This recognition does not date from 2000. It is the explicit teaching of the Second Vatican Council in the decree on ecumenism Unitatis Redintegratio (1964), which devotes an entire section to the Eastern Churches^[7]. The conciliar text is highly precise:

"These Churches, although separated from us, yet possess true sacraments, above all — by apostolic succession — the priesthood and the Eucharist, whereby they are still joined to us in closest intimacy." — Second Vatican Council, Unitatis Redintegratio, §15^[8]

Three realities are recognized as valid without the slightest reservation: the apostolic succession of bishops (the unbroken chain going back to the Apostles through the laying on of hands), the ordained priesthood, and the Eucharist. For Catholic theology, these three realities stand together: because Orthodox bishops are validly ordained, their priests are too, and because these priests are validly ordained, their Mass truly consecrates the Body and Blood of Christ. The Catechism takes up this teaching word for word in the eucharistic context^[9].

Why the Church Does NOT Say the Same Thing About Protestants

The best way to measure the scope of this recognition is to compare it with what the Church says about the communities born of the Reformation. Dominus Iesus draws the dividing line with deliberate sharpness:

"The ecclesial communities which have not preserved the valid Episcopate and the genuine and integral substance of the Eucharistic mystery, are not Churches in the proper sense." — Congregation for the Doctrine of the Faith, Dominus Iesus, §17^[10]

The difference does not lie in sincerity of faith or fervor of prayer, which can be very great among Protestants. It lies in the sacramental structure. Lacking an episcopate in apostolic succession, the communities of the Reformation have not preserved the sacrament of Holy Orders, and therefore do not have the Eucharist in the Catholic sense. That is why the Church calls them "ecclesial Communities" and not "Churches" in the proper sense, while she calls the Orthodox "Churches" without restrictive quotation marks. The following table summarizes this difference of status:

This asymmetry explains everything else: it is because the Orthodox kept the sacraments that communion with them can be described as "so profound," whereas with Protestants it remains, in the words of the Catechism, more limited^[11].

The concept that structures all Catholic teaching on the Orthodox is that of imperfect communion. It must be understood precisely, for it escapes the two opposite caricatures: neither "they are already just like us," nor "they are outside the Church."

What "Imperfect Communion" Means

The Catechism lays down the general principle that holds for all non-Catholic baptized Christians, before applying it to the Orthodox:

"Those who believe in Christ and have been properly baptized are put in a certain, although imperfect, communion with the Catholic Church." — Catechism of the Catholic Church, §838^[12]

"Imperfect communion" is not a false or fictitious communion: it is a communion that is real but unfinished. The right image is not that of a wall dividing, but of a bond already tied that has not yet reached its full tension. Vatican II had grounded this idea by teaching, in Lumen Gentium, that the Church knows herself to be joined in many ways to all the baptized who honor Scripture and receive the sacraments^[13]. With the Orthodox, who possess all the sacraments, this union reaches its highest degree outside full communion.

"It Lacks Little…": Eucharistic Closeness

This is where the strongest phrase of §838 comes in, already quoted: with the Orthodox, "it lacks little" for celebrating the Eucharist together. This formula is borrowed from an address by Paul VI delivered on 14 December 1975, for the tenth anniversary of the lifting of the anathemas^[14]. It says something staggering: the barrier between Catholics and Orthodox is not sacramental. Both Churches confess the same eucharistic faith, the same priesthood, the same seven sacraments, the same Mother of God, the same seven ecumenical councils of the first millennium. What still prevents sharing the same altar belongs to the structure of communion — in other words, to the visible bond with Rome — and not to the substance of sacramental faith.

Common Baptism, Root of Communion

At the root of all this communion lies a sacrament that Catholics and Orthodox recognize in each other mutually and unconditionally: baptism. The Church teaches that baptism "constitutes the foundation of communion among all Christians"^[15]. An Orthodox Christian who is baptized therefore never needs to be rebaptized in order to become Catholic, and vice versa: the sacrament received is fully valid. It is this common baptismal root that makes the division between Rome and the East never, for Catholic doctrine, a separation between the Church and the "outside," but a fracture within the people of the baptized.

Among the formulas most used in dialogue with Orthodoxy is that of "sister Churches." It is beautiful and true, but the Church has been careful to specify its exact use, lest it be made to say what it does not say.

The Magisterial Use of "Sister Churches"

The expression has been taken up by the popes themselves. John Paul II uses it in Ut Unum Sint to describe the recovered fraternity between Rome and Constantinople^[16]. It conveys a real truth: the particular Churches of East and West were born of the same apostolic seed, grew up side by side, and share the same sacramental heritage. An Orthodox metropolis and a Catholic diocese are, in this sense, sister Churches — daughters of one mother, the one Church of Christ.

The 2000 Clarification: A Fraternity Properly Understood

But the expression can mislead if wrongly applied. In 2000, a Note on the Expression "Sister Churches" published by the Congregation for the Doctrine of the Faith set limits to its use^[17]. The central idea is simple: one may speak of "sister Churches" between particular Churches (such an Orthodox patriarchate and such a Catholic diocese), but never in the sense that the "Catholic Church" as a whole would simply be the "sister" of the "Orthodox Church" as a whole, as if there were two Churches side by side and neither of them were the Church of Christ. For according to Catholic faith, the one Church of Christ subsists in the Catholic Church^[18]. The fraternity is therefore real between particular Churches, but it does not dissolve the affirmation that the fullness of the Church is found in Catholic communion.

If communion is so profound, why is it not complete? The Church's answer is constant: what is lacking is full communion with the Bishop of Rome.

The Roman Primacy, an Internal Constitutive Principle

For Catholic doctrine, communion with the successor of Peter is not an external supplement added to an otherwise complete Church: it is one of its internal constitutive principles. Dominus Iesus puts it thus: because communion with the Catholic Church, whose visible head is the Bishop of Rome, "is not some external complement to a particular Church but rather one of its internal constitutive principles," the situation of the Orthodox Churches, despite their full sacramental validity, "suffers from a defect"^[19]. It is precisely this point — the role of the Pope — that constitutes the heart of the divergence, and it is treated in detail, with the biblical and patristic arguments, in Answers to Orthodox Objections.

A Reciprocal "Wound," Not a Condemnation

The vocabulary the Church chooses to describe this situation is revealing. In its Responses to Some Questions Regarding Certain Aspects of the Doctrine on the Church (2007), the Congregation for the Doctrine of the Faith speaks not of nullity but of a wound:

"These are Churches which, although separated, remain united to the Catholic Church by very close bonds, such as apostolic succession and a valid Eucharist; yet something is lacking in their condition as particular Churches." — Congregation for the Doctrine of the Faith, Responses on the Doctrine of the Church, 2007^[20]

The word "wound" says two things at once: that something really is lacking (this is not a matter of indifference), and that this lack affects a living body (it is not a death). The division is an open wound in the one Church, and this wound also injures, in another way, the Catholic Church herself, hindered from fully realizing her catholicity in history^[21]. That is why the Church never treats the Orthodox as defeated adversaries, but as brothers whose separation is a shared suffering.

The recognition of Orthodox sacraments is not theoretical: it has concrete practical consequences, inscribed in the law of the Church. This is doubtless the least known aspect of Catholic teaching on the Orthodox.

Canon 844: Communicatio in Sacris with the Orthodox

The 1983 Code of Canon Law provides that a Catholic faithful may, in certain circumstances, receive three sacraments from an Orthodox minister, and that a Catholic priest may administer them to an Orthodox Christian who freely asks for them:

"Catholic ministers administer the sacraments of penance, Eucharist, and anointing of the sick licitly to members of Eastern Churches which do not have full communion with the Catholic Church if they seek such on their own accord and are properly disposed." — Code of Canon Law, canon 844 §3^[22]

This possibility, called communicatio in sacris, was already envisaged by Vatican II, which judged it not only "possible" but, in suitable circumstances and with the approval of authority, "even to be recommended"^[23]. It exists only because Orthodox sacraments are recognized as valid: the same could not be said of Protestant communities, whose Eucharist is not recognized. It is the most tangible proof that the teaching on "real communion" is not mere words, but a juridical reality.

No New Baptism, No "Reconversion"

Likewise, when an Orthodox Christian enters into full communion with the Catholic Church, he receives no new baptism nor new ordination if he is a priest: his sacraments are valid. In this case the Church does not even speak of "conversion" in the sense of a passage from paganism to the faith, but of a restoration of full communion. The vocabulary is deliberately different from what would be used for a non-baptized person.

Marriages, Funerals and Concrete Pastoral Life

In daily life, this closeness translates into many pastoral accommodations: mutual recognition of validly celebrated marriages, the possibility for a Catholic to attend the Orthodox Divine Liturgy and partly satisfy his desire for prayer there, particular provisions for mixed couples. All of this flows from a single principle: between Catholics and Orthodox, we are not strangers in sacramental faith, but separated members of one family.

Many imagine that Catholics and Orthodox remain under the excommunications of 1054. This has no longer been the case since 1965, and this gesture is an integral part of what the Church says today about the Orthodox.

The Joint Declaration of Paul VI and Athenagoras

On 7 December 1965, on the eve of the closing of the Second Vatican Council, Pope Paul VI and Ecumenical Patriarch Athenagoras I published a joint declaration, read simultaneously in Rome and at the Phanar (Constantinople). The two Churches took a solemn decision:

"[Paul VI and Athenagoras I] regret the offensive words, the reproaches without foundation, and the reprehensible gestures which […] marked or accompanied the sad events of that period […] [and] likewise regret and remove from memory and from the midst of the Church the sentences of excommunication [of 1054], the memory of which still acts even today as an obstacle to rapprochement […] and consign them to oblivion." — Joint Declaration of Paul VI and Athenagoras I, 7 December 1965^[24]

This gesture was the culmination of the historic meeting of Paul VI and Athenagoras at Jerusalem in January 1964 — the first meeting between a Pope and a Patriarch of Constantinople since the Council of Florence (1439)^[25].

"Consigning to Oblivion": Scope and Limits of the Gesture

One must understand exactly what this gesture does, and what it does not do. It erases from the Church's memory the reciprocal sentences of excommunication of 1054 and the bitterness surrounding them: on the canonical and psychological plane, the obstacle is lifted. But it does not, by itself, restore full communion: the underlying doctrinal divergences (primacy, the Filioque, recent Marian dogmas) remain to be resolved. John Paul II would recall: the lifting of the excommunications removed a painful obstacle without thereby closing the journey^[26]. It is an immense step, but a step, not the arrival.

Catholic teaching on the Orthodox is not merely a static observation: it is oriented toward a declared goal, the restoration of full communion. This is the constant teaching of the popes since Vatican II.

"Breathing with Both Lungs"

The most famous image is that of John Paul II, in the encyclical Ut Unum Sint (1995), entirely devoted to ecumenical commitment:

"The Church must breathe with her two lungs!" — Saint John Paul II, Ut Unum Sint, §54^[27]

The image says that the Christian East is not an exotic appendage nor a distant dependency of the Latin West: it is one of the two lungs of a single body, without which the whole Church breathes poorly. In the same year, in the apostolic letter Orientale Lumen, John Paul II invited Catholics to know, love and receive the spiritual, liturgical and theological treasure of the East — the theology of the Greek Fathers, the prayer of the heart, the spirituality of deification, the beauty of icons^[28].

The Official Theological Dialogue: Ravenna and Chieti

This desire for unity takes flesh in an institutional theological dialogue. The Joint International Commission for Dialogue between the Catholic Church and the Orthodox Church, created in 1979, works precisely on the point that still separates: how to articulate primacy (the role of the Pope) and synodality (the collegial governance dear to the East). The Ravenna document (2007) jointly recognized the need for a primacy at the local, regional and universal levels, without yet defining how it should be exercised^[29]. The Chieti document (2016) returned to the common tradition of the first millennium — before the rupture — as a normative basis for both Churches^[30]. The path is slow, but it is real and it is moving forward.

The Rejection of "Uniatism" as a Method

One delicate point deserves to be named. The Catholic Church has clearly stated that unity is no longer sought through "uniatism" — that is, through the rallying of isolated Orthodox groups detached from their Church. The Balamand document (1993), fruit of the official dialogue, recognized that this method of the past could no longer be the model of the unity sought, while affirming the right to exist of the already constituted Eastern Catholic Churches^[31]. The unity aimed at is not absorption, but a communion in the legitimate diversity of traditions.

Praying and Hoping for Unity

Finally, the Church's teaching stresses that unity is first of all a gift of God to be asked for, not a mere negotiation. Spiritual ecumenism — prayer, conversion of heart, holiness of life — is presented by Vatican II as "the soul of the whole ecumenical movement"^[32]. Successive popes have asked forgiveness for the faults of Catholics in past divisions, and have multiplied gestures of fraternity with the Patriarchs of the East. Unity remains a horizon; but it is held to be possible, because, from the standpoint of sacramental faith, "it lacks little."

To conclude, it is useful to list negatively what the Church, contrary to widespread opinion, does not say about the Orthodox. Several common ideas are misunderstandings that the magisterial texts refute.

The Church does not say that the Orthodox are "of another religion": they confess the same Trinitarian faith, the same Christ, the same sacraments. She does not say that their Eucharist is "symbolic" or "invalid": she holds it to be the true Body of Christ. She does not say that they must be "rebaptized": their baptism is fully recognized. She does not say that they are "outside the Church" in the strict sense: they are in real, though imperfect, communion. She does not treat them as "heretics" in the popular and defamatory sense of the word: the divergence concerns the structure of communion and a few precise doctrinal points, not the heart of the common faith. And she does not say that the situation is "a matter of indifference" or definitive: the division is a wound to be healed, and the restoration of full unity is a duty.

The following table recapitulates what the Church affirms and what she refuses to say:

In short, the Catholic position holds together two affirmations that one might be tempted to oppose: immense respect for the sacramental, liturgical and spiritual richness of Orthodoxy, and the firm conviction that the fullness of the unity willed by Christ passes through communion with Peter. Neither contempt nor relativism: a lucid and hopeful fraternity.

• The Great Schism of the East — the detailed history of the 1054 rupture, its political, cultural and theological causes.
• The Photian Schism — the first great crisis between Rome and Constantinople (867-880).
• Answers to Orthodox Objections — the reasoned response on Roman primacy, the Filioque and the Council of Florence.
• The Eastern Catholic Churches — the 23 Eastern-rite Churches in full communion with Rome, not to be confused with the Orthodox.