What are the Differences between Catholics and Orthodox?

In the broad landscape of Christianity, the Eastern Catholic Churches and the Orthodox Churches share deep historical roots and a rich spiritual heritage. Yet, they have followed opposite paths.

The Eastern Catholic Churches are those Christian communities of Eastern tradition that maintain full communion with the Bishop of Rome, the Pope. Therefore, they recognize his universal primacy. Despite this communion, they preserve their own particular liturgies, spiritualities, and ecclesiastical disciplines.

On the other hand, the Orthodox—also known as Eastern or Byzantine Orthodox Churches—form a communion of self-governing (autocephalous) churches that do not accept the universal primacy of the Pope as understood by Rome. They see themselves as the continuation of the original Christian Church in the East.

Though at first glance they may seem very similar—and indeed share much of their history—Catholics and Orthodox do not practice or experience their faith in exactly the same way.

This article will explore the main similarities and differences between Eastern Catholics and Orthodox Christians.

Common Roots between Catholics and Orthodox

Catholics and Orthodox share a common origin that goes back to the Twelve Apostles. These took the Gospel from the Eastern Mediterranean to the entire known world. Many patriarchates, both Catholic and Orthodox, claim a direct apostolic foundation.

The Ecumenical Councils

Doctrinally, both traditions accept the theological and canonical foundations established by the first seven Ecumenical Councils, held when the Church was still united.

These councils brought together bishops from across the known world to define the faith and resolve doctrinal disputes. The key councils shaping the common history of Catholics and Orthodox include:

• First Council of Nicaea (325):

Convened by Emperor Constantine, it affirmed that Jesus Christ is consubstantial with the Father (against Arianism), approved the Nicene Creed, and recognized a primacy of honor for the Bishop of Rome and the historical patriarchates (Rome, Alexandria, Antioch, Jerusalem).

• First Council of Constantinople (381)

Expanded the Creed to define the divinity of the Holy Spirit and confirmed the order of primacy with Rome first and Constantinople second, “as the New Rome.”

• Council of Ephesus (431)

Declared the Virgin Mary as Theotokos (“Mother of God”), opposing Nestorianism, and reaffirmed the unity of Christ as one divine person with two natures.

• Council of Chalcedon (451)

Defined the doctrine of the two natures of Christ, “without confusion or division.”

This council led to a split with some Eastern churches (Coptic, Armenian, Syrian), which did not accept Chalcedon and formed the so-called non-Chalcedonian Oriental Orthodox Churches.

• II and III Council of Constantinople (553 and 680-681)

Further clarified the understanding of Christ’s two natures and wills.

• Second Council of Nicaea (787)

Restored the veneration of icons against iconoclasm. This is the last council mutually accepted by both Catholics and Byzantine Orthodox.

Doctrinal Similarities between Catholics and Orthodox

Because both Catholics and Orthodox accept these first seven councils, they share the same core beliefs about the nature of Christ and the Holy Trinity.

• Holy Trinity

Both traditions profess one God in three distinct but equal Persons: Father, Son, and Holy Spirit. This belief is central to their faith and spirituality.

• Jesus Christ

Both believe Jesus Christ is truly God and truly man—the Son of God who became man for humanity’s salvation. .

The resurrection of Christ on the third day forms the foundation of hope and salvation for believers.

• Sacraments

Catholics and Orthodox share seven sacraments—Baptism, Chrismation (Confirmation), Eucharist, Confession, Anointing of the Sick, Holy Orders, and Marriage. In the East, these are often called “mysteries” to emphasize their divine and transformative nature.

• Scripture and Tradition

Both Churches recognize Sacred Scripture as the written testimony of God’s revelation.

They also uphold Tradition, which includes the teachings of the Church Fathers, decisions of the ecumenical councils, liturgical practices, and lives of the saints.

The Holy Spirit works through both Scripture and Tradition.

• Devotion to the Blessed Virgin and the saints

Both share deep devotion to the saints, especially the Virgin Mary, honored as Theotokos (Mother of God), and believe in her intercession.

Icons—sacred images—play a central role in spiritual life, seen as true “windows to the divine.”

The Great Schism of 1054

The split between Catholics and Orthodox was not sudden but the result of centuries of growing tensions.

It began in 395 AD, when Emperor Theodosius I divided the Roman Empire into two halves: the Western Latin-speaking half centered in Rome, and the Eastern Greek-speaking half centered in Constantinople, the “New Rome.”

Each half developed distinct cultures and priorities. The West, interacting with new peoples, adapted to a changing environment. The East, more stable and wealthy, cultivated a traditional and luxurious style. The Church did not escape these differences.

In Constantinople, the Byzantine emperor exercised significant influence over church affairs—a practice known as caesaropapism—that Rome rejected.

The Great Schism of 1054 was the culmination of this long estrangement. The papal legates and the Patriarch of Constantinople excommunicated each other, breaking Church unity.

Key causes included doctrinal disagreements about the Holy Spirit, papal authority, the use of icons, different types of bread for the Eucharist, and clerical celibacy.

Doctrinal Differences between Catholics and Orthodox

The main differences between Catholics and Orthodox do not lie in fundamental beliefs about God or Jesus Christ. Instead, they arise from doctrinal and moral definitions developed after the first seven councils, as well as church governance and certain liturgical practices that contributed to the schism.

Issues like the Filioque and papal authority, which we will explore, reflect different understandings of the Trinity’s internal relationship or Church governance, without affecting essential beliefs about the Holy Trinity or the person of Christ.

The Papal Primacy

The Catholic Church teaches that the Pope, as Bishop of Rome and successor of Saint Peter, holds universal jurisdiction over the entire Church, including supreme authority in faith, morals, and governance. Eastern Catholic Churches recognize and fully submit to this authority.

In contrast, the Orthodox Churches do not accept the Pope’s universal jurisdiction. They regard the Bishop of Rome as holding a “primacy of honor” (primus inter pares—“first among equals”) among the patriarchs, but not as a supreme, universal authority over other patriarchates.

For the Orthodox, authority is shared among self-governing churches and their patriarchs, with decisions made collegially through councils.

The Filioque Clause

Catholics believe the Holy Spirit proceeds from the Father and the Son. The Latin Rite includes the Filioque (“and the Son”) in the Nicene-Constantinopolitan Creed.

Orthodox reject the addition of the Filioque, maintaining the original text that the Holy Spirit proceeds only from the Father. The Catholic Church clarifies this means “from one principle.”

They argue that the Father is the sole source of divinity within the Trinity, so adding the Son would imply two origins for the Spirit. The Orthodox see this as a theological error and an unauthorized alteration of an ecumenical creed.

Purgatory

The Catholic Church teaches Purgatory as a temporary state of purification after death for souls who die in God’s grace but are not yet perfectly purified.

These souls suffer to atone for the temporal punishment due to forgiven sins and to cleanse venial sins. Prayers for the deceased, Masses offered in their favor, and indulgences help these souls.

Orthodox do not have a formal doctrine of Purgatory as a distinct purifying fire They believe souls await the Final Judgment after death, and may undergo purification through prayers and good works of the living Church.

They reject the Western concept of purifying fire and indulgences as understood in Catholicism.

Original Sin vs. Ancestral Sin

Catholics teach that original sin is the deprivation of original holiness and justice inherited by all humanity due to Adam and Eve’s disobedience. It is seen as a sin “contracted,” not “committed,” that wounds human nature and inclines it to sin (concupiscence). Baptism removes original sin.

The Orthodox Churches prefer the term “ancestral sin”. They believe that humanity inherits the consequences of the sin of Adam and Eve, mainly death, corruption, and a fallen condition or disease of human nature, but not their personal guilt. Each person is responsible for their own sins. Salvation is seen as a process of deification (theosis), a progressive union with God, which requires human cooperation (synergy) with divine grace.

The Immaculate Conception

The Immaculate Conception is a Catholic dogma, defined in 1854, teaching that the Virgin Mary was preserved from all stain of original sin from the moment of her conception by a singular grace of God in view of Christ’s merits.

Orthodox venerate the Virgin Mary as Theotokos and believe in her exceptional purity and holiness. However, they do not accept the dogma of the Immaculate Conception as defined by Rome. Some consider it a “Roman novelty”. While they believe Mary was purified during her life, they generally do not affirm her conception without original sin.

Liturgical and Sacramental Variations

Eucharist

For consecration, the Catholic Church uses unleavened bread (hosts). Orthodox use leavened bread.

Catholics believe in transubstantiation, that is, the miracle by which bread and wine become the Body and Blood of Christ, with the substance changing but the accidents (appearance) remaining. The Orthodox Church accepts the real presence of Christ in the Eucharist, but does not use the term “transubstantiation” to explain this change. Considers that the way in which bread and wine become the body and blood of Christ is a mystery that cannot be fully explained.

Catholics typically give First Communion after children reach the age of reason, while Orthodox administer Communion to infants immediately after Baptism and Chrismation.

During consecration, Orthodox and Eastern Catholics emphasize the epiclesis—the invocation of the Holy Spirit to transform the bread and wine—whereas Catholics emphasize the words of institution.

Baptism and Chrismation/Confirmation

Catholic baptism is usually by pouring or sprinkling water on the head; Confirmation is typically administered later by a bishop.

Orthodox baptize by triple immersion of the whole body followed immediately by Chrismation (Confirmation) administered by a priest using chrism consecrated by a bishop.

Priestly Celibacy

The Latin Catholic Church requires celibacy for all aspirants to the priesthood. While, los Eastern Catholics and Orthodox allow married men to be ordained priests and deacons. But they must have married before ordination. However, bishops must be celibate and are usually chosen from among the monastic ranks.

Veneration of Icons and Statues

The Catholic Church uses both two-dimensional images (icons, paintings) and three-dimensional statues to inspire piety and venerate saints. Orthodox and Eastern Catholics prefer icons to images.

Liturgical Calendar

Catholics follow the Gregorian calendar, adopted in 1582. For their part, most Orthodox Churches continue to follow the Julian calendar, which is currently 13 days behind the Gregorian calendar.

This results in different dates for fixed holidays such as Christmas (January 7 for the Julian calendar) and Easter (which is calculated differently, often leading to different dates). Some Eastern Catholic Churches also use the Julian calendar.

Form of Government

The Catholic Church has a centralized, hierarchical structure under the universal primacy of the Pope.

The Orthodox model emphasizes conciliar and decentralized unity based on shared faith and sacraments among independent churches, many with ethnic foundations—Greek, Russian, Serbian, etc.

The Orthodox Church is a communion of distinct, independent, and autocephalous (self-governed) churches. Each autocephalous church governs itself through its own synod and primate (patriarch, archbishop, or metropolitan).

The Patriarch of Constantinople (Ecumenical Patriarch) is recognized as the “first among equals” (primus inter pares) among the Orthodox primates, holding a primacy of honor. But he has no direct authority over other autocephalous churches.

Some churches are “autonomous”, which means they have a degree of self-government. However, the confirmation or consecration of their primate depends on an autocephalous mother church.

Despite their administrative independence, these churches maintain doctrinal and sacramental unity. Each Orthodox Church recognizes the validity of the others.

Ecumenical Dialogue between Catholics and Orthodox

The path toward dialogue has been marked by attempts at union and deep resistance.
The Council of Florence (1438-1445) achieved agreements on issues like the Filioque and papal primacy but was rejected in Constantinople, largely due to opposition from figures like Mark of Ephesus and the difficulty of reconciling Western scholastic and Eastern patristic perspectives.

Later efforts, such as the Union of Brest (1596), which led to the creation of Eastern Catholic Churches like the Ukrainian Greek Catholic Church, showed that reconciliation requires more than theological consensus—it also needs healing historical wounds and respecting cultural sensitivities.

In modern times, Vatican II (1962-1965) opened a new chapter, describing the Church as a “mystery of communion” and setting a foundation for fraternal dialogue. A notable milestone was the Ravenna Document (2007), where Catholics and Orthodox recognized Rome’s “first place” in the first millennium and the Bishop of Rome as protos among patriarchs, though without agreement on the scope of his authority.

Historic gestures like the meeting between Pope Paul VI and Ecumenical Patriarch Athenagoras I in 1964—which culminated in the mutual lifting of the excommunications of 1054—ushered in a period of warmer relations and greater mutual understanding.

Today, both Churches recognize the validity of each other’s sacraments, reflecting a real spiritual unity, even if full institutional communion remains elusive.

Unity of Christians

Though the Great Schism fractured communion between Eastern and Western Christianity, the echo of Jesus’ prayer resonates powerfully in today’s ecumenical dialogues.

That all may be one, as you and I are one ($$Jn$$17:21).

This prayer reminds us not only of the unity that existed in the early Church but calls urgently for future unity.

As we have seen, the Catholic and Orthodox Churches are not identical, but neither are they strangers. They share an invaluable spiritual and doctrinal treasure: a common faith, valid sacraments, and apostolic succession.

Differences over papal primacy, the Filioque, or liturgical practices, while significant, are points for fraternal dialogue—not insurmountable walls.

Progress in mutual understanding shows division can be overcome. The goal of unity is not uniformity, but full communion where each tradition can flourish with its unique richness.

Jesus’ prayer for unity invites us to look beyond historical and cultural differences to rediscover what unites us: one Lord, one faith, one baptism.

On this journey, every step toward understanding and forgiveness brings us closer to Christ’s desire, offering the world a more powerful witness of His love. Christian unity is not just a hope but a divine mandate—a living sign that God is present among us.