Catholic Church vs Orthodox Church — what is the difference?

By Vinay Koshy, Editor

The Catholic Church and the Orthodox Church share the first thousand years of Christian history, then split in 1054 over papal authority, the Filioque clause, and how church councils reach binding decisions. Both keep bishops, seven sacraments, apostolic succession, and reverence for Mary and the saints. The Catholic Church answers to Rome under one Pope. Orthodoxy is a family of self-governing churches with no single earthly head.

Last verified: 2026-07-04. Figures sourced from the 2021 Australian Census and the Australian Church Directory (July 2026).

Comparison at a glance

Aspect	Catholic Church	Orthodox Church
Formal separation date	Great Schism of 1054 — mutual excommunications between Rome and Constantinople, lifted in 1965 but the split remains.	Same date; both traditions trace continuous existence back to the apostles.
Head of the Church	The Pope, Bishop of Rome, holds universal jurisdiction. Currently Pope Leo XIV (Robert Francis Prevost, elected 8 May 2025).	No single head. A family of self-governing (autocephalous) churches, each led by a Patriarch or Archbishop. The Ecumenical Patriarch of Constantinople is first among equals in Eastern Orthodoxy.
Papal infallibility	Defined dogma at Vatican I (1870). The Pope, when defining a doctrine of faith or morals ex cathedra, is preserved from error.	Rejected. Doctrine is defined by ecumenical councils in the Spirit, not by any single bishop.
Filioque in the Nicene Creed	The Holy Spirit proceeds from the Father and the Son (Filioque added by the Western church from around the 6th century).	The Holy Spirit proceeds from the Father alone, per the original 381 AD Creed of Constantinople.
Purgatory	Doctrine of purgatory as an intermediate state of purification after death.	No formal doctrine of purgatory. Prayer for the dead is practised, but the intermediate state is treated as a mystery.
Immaculate Conception of Mary	Dogma since 1854: Mary was conceived free from original sin.	Not held as dogma. Orthodoxy honours Mary as Theotokos (God-bearer) and celebrates her Conception, but does not accept the specific Western formulation of original sin it presupposes.
Priestly marriage	Latin Rite priests are required to be celibate. Eastern Catholic Rites in communion with Rome may ordain married men.	Married men may be ordained deacons and priests. Marriage must occur before ordination. Bishops are drawn from unmarried clergy (usually monastics).
Divorce and remarriage	Marriage is indissoluble; annulment (a declaration that a valid marriage never existed) is the only path to remarriage in the church.	Remarriage is permitted under the principle of economia — up to three marriages in total, with each subsequent rite becoming increasingly penitential.
Liturgical calendar	Gregorian calendar for all feasts including Easter.	Most Orthodox churches use the Julian calendar for fixed feasts and/or for Pascha. The Ecumenical Patriarchate and Greek Orthodox follow the Revised Julian for fixed feasts but keep Julian Pascha.
Members in Australia (2021 Census)	5,075,907 (20.0% of Australians) — the single largest religious affiliation in the country.	594,458 Eastern Orthodox (2.3%) plus 111,120 Oriental Orthodox (0.4%). Combined about 2.8%.
Directory listings	2,157 parishes across all 8 states and territories.	343 churches across 13 distinct jurisdictions. Greek Orthodox is the largest at 139 listings; Coptic Orthodox 42; Serbian 44; Russian 30; Macedonian 26; Antiochian 17.
Community services in Australia	CatholicCare, Vinnies (St Vincent de Paul), MacKillop Family Services, Catholic Health Australia, and diocesan agencies.	Community services vary by jurisdiction. Greek Welfare, St Basil's Homes for the Aged, and diocesan philanthropic committees are the largest umbrellas.

Origin and the Great Schism

Both churches trace their existence to the apostles and share the first seven ecumenical councils (325 to 787 AD), the New Testament canon, the Nicene-Constantinopolitan Creed (before the Filioque was added in the West), the veneration of icons, monasticism, and the seven sacraments. For the first thousand years they were, with fluctuating tension, parts of one visible Church divided between Latin-speaking Rome and Greek-speaking Constantinople.

The Great Schism of 1054 is the traditional date of the split, when Cardinal Humbert delivered a bull of excommunication to Patriarch Michael Cerularius in Hagia Sophia, and the Patriarch replied in kind. In practice the separation had been building for centuries over language, liturgy, papal claims of universal jurisdiction, and the Western addition of the Filioque to the Creed. The final rupture came with the sack of Constantinople by the Fourth Crusade in 1204. The mutual excommunications of 1054 were formally lifted by Pope Paul VI and Ecumenical Patriarch Athenagoras in 1965, but the churches remain out of communion.

Governance — one Pope or many patriarchs?

This is the most visible structural difference. The Catholic Church is governed by the Pope, the Bishop of Rome, who holds universal jurisdiction over every Catholic diocese in the world. The College of Bishops teaches in communion with him. Pope Leo XIV (Robert Francis Prevost, the first US-born pope) was elected on 8 May 2025. In Australia, five Latin-Rite metropolitan archdioceses (Sydney, Melbourne, Brisbane, Perth, and Adelaide), two additional Latin-Rite archdioceses that are not metropolitan sees (Canberra-Goulburn and Hobart), 21 suffragan dioceses, five Eastern Catholic eparchies, and the Military Ordinariate and Personal Ordinariate report through the Australian Catholic Bishops Conference to Rome.

Orthodoxy is a communion of self-governing (autocephalous) churches. There is no single earthly head. Each autocephalous church is led by its own Patriarch, Archbishop, or Metropolitan, elected by that church's synod of bishops. The Ecumenical Patriarch of Constantinople holds a primacy of honour (first among equals) in the Eastern Orthodox family, but no jurisdiction outside his own territory. In Australia the largest is the Greek Orthodox Archdiocese of Australia, part of the Ecumenical Patriarchate; separate jurisdictions cover the Serbian, Russian, Antiochian, Macedonian, Romanian, Bulgarian, and Ukrainian Orthodox communities. The Oriental Orthodox family, doctrinally distinct from Eastern Orthodox on Christology, includes the Coptic Orthodox Diocese of Sydney and Affiliated Regions, and the Ethiopian and Eritrean Orthodox jurisdictions.

Theology — Filioque, purgatory, and papal infallibility

The Filioque is the Latin phrase meaning "and from the Son." The original 381 AD Creed said the Holy Spirit "proceeds from the Father." The West added "and from the Son" from around the 6th century, ratified for Rome in 1014. Orthodoxy rejects the addition on two grounds. First, it was made unilaterally without the consent of an ecumenical council. Second, it obscures the Father's unique role as the sole source (monarchia) of the Trinity. Ecumenical dialogue since Vatican II has narrowed the theological gap, but the addition itself remains a live issue.

Papal infallibility was defined at the First Vatican Council in 1870. The Pope, when speaking ex cathedra on a matter of faith or morals, is preserved from error. The doctrine has been invoked twice: the Immaculate Conception of Mary (1854) and the Assumption of Mary (1950). Orthodoxy rejects the entire concept, holding that binding doctrine can only be defined by an ecumenical council acting in the Spirit.

Catholic teaching includes purgatory as an intermediate state of purification after death for those who die in God's grace but are not yet perfectly holy. Orthodoxy has no formal doctrine of purgatory; it prays for the dead and holds that the state after death is a mystery not to be defined further. Both churches practise prayers, memorial services, and requiems for the departed.

Worship and liturgy

Catholic worship in Australia is predominantly the Roman Rite Mass in English, revised after Vatican II (1962-1965). Latin Mass communities exist in most capital cities. The Divine Office (Liturgy of the Hours) structures daily prayer for clergy and religious.

Orthodox worship is the Divine Liturgy, most commonly the Liturgy of Saint John Chrysostom in Eastern Orthodox parishes and the Coptic Rite in Coptic Orthodox parishes. Language varies by jurisdiction: Greek Orthodox parishes typically use Greek with English readings; Serbian parishes use Church Slavonic and Serbian; Russian parishes use Church Slavonic; Antiochian parishes use Arabic and English; Coptic parishes use Coptic and Arabic; and newer jurisdictions in Australia are increasingly bilingual. Icons occupy the iconostasis (a screen separating the sanctuary from the nave), and standing rather than kneeling is the traditional posture for prayer.

Orthodox jurisdictions in Australia

Orthodoxy in Australia is not a single institution but a family of national and cultural jurisdictions, each self-governing under a different mother church. The directory lists 343 Orthodox churches across 13 jurisdictions:

Greek Orthodox Archdiocese of Australia — 139 parishes, under the Ecumenical Patriarchate of Constantinople.
Serbian Orthodox Metropolitanate of Australia and New Zealand — 44 parishes.
Coptic Orthodox Diocese of Sydney and Affiliated Regions — 42 parishes (Oriental Orthodox family).
Russian Orthodox Church Outside Russia (ROCOR), Diocese of Australia and New Zealand — 30 parishes.
Macedonian Orthodox Diocese of Australia and New Zealand — 26 parishes.
Antiochian Orthodox Archdiocese of Australia, New Zealand and the Philippines — 17 parishes.
Malankara Orthodox Syrian Church (Indian Orthodox) — 8 parishes (Oriental Orthodox family).
Ethiopian and Eritrean Orthodox Tewahedo Church — 5 parishes (Oriental Orthodox family).
Ukrainian Orthodox Church — 3 parishes.
Romanian Orthodox Church, Diocese of Australia and New Zealand — 3 parishes.
Syriac Orthodox Church — 2 parishes (Oriental Orthodox family).
Bulgarian Orthodox Church — 1 parish.
Generic Orthodox listings (jurisdictional affiliation not specified) — 23 parishes.

Eastern Catholic churches — Catholic doctrine, Byzantine or Antiochene worship

A common source of confusion is the Eastern Catholic Churches. These sui iurischurches use Byzantine, Alexandrian, Antiochene, Armenian, or East Syriac liturgical traditions and often look Orthodox to a visitor — icons, chanted Divine Liturgy, married clergy — but they are in full communion with Rome and accept the Pope's universal jurisdiction. Doctrinally they are Catholic; liturgically they preserve the ancient Eastern rites. Five Eastern Catholic eparchies operate in Australia under the Australian Catholic Bishops Conference:

Maronite Catholic Eparchy of Saint Maron of Sydney — 9 parishes serving roughly 160,000 Maronite Catholics of Lebanese heritage. Antiochene liturgy in Syriac, Arabic, and English.
Melkite Catholic Eparchy of Saint Michael's of Sydney — 9 parishes serving roughly 45,000 Melkite Greek Catholics of Syrian and Lebanese heritage. Byzantine liturgy in Arabic, Greek, and English.
Ukrainian Catholic Eparchy of Saints Peter and Paul of Melbourne — 8 parishes serving roughly 35,400 Ukrainian Catholics. Byzantine liturgy in Ukrainian and English.
Syro-Malabar Catholic Eparchy of Saint Thomas the Apostle of Melbourne — the sole Syro-Malabar eparchy in Oceania, serving Kerala Indian Catholics. East Syriac liturgy in Malayalam and English.
Chaldean Catholic Eparchy of Saint Thomas the Apostle of Sydney — serving Assyrian and Chaldean Catholics of Iraqi heritage. East Syriac liturgy in Aramaic and English.

Armenian, Coptic, Syro-Malankara, and Ethiopian Catholics also worship in Australia through parish communities that do not yet have their own eparchy. In the Australian Church Directory, Eastern Catholic parishes are rolled into the broader Catholic denomination bucket because members self-identify as Catholic on the ABS Census.

Frequently asked questions

Are the Catholic and Orthodox Churches in communion with each other?

No. They have been formally out of communion since the Great Schism of 1054, when the Patriarch of Constantinople and the Pope's legate mutually excommunicated each other. Members of one church cannot receive Holy Communion at the other in ordinary circumstances. The excommunications were lifted in 1965 as a gesture of goodwill, but the formal split over papal authority, the Filioque, and other issues remains.

What is the single biggest theological difference?

The scope of papal authority. The Catholic Church holds that the Bishop of Rome (the Pope) has universal jurisdiction over the whole Church and, when speaking ex cathedra on faith and morals, is infallible. Orthodoxy rejects both universal papal jurisdiction and papal infallibility. It holds that the Bishop of Rome is a first-among-equals — historically the senior patriarch when in communion — but has no unilateral authority over the other patriarchates.

What is the Filioque and why does it matter?

The Filioque is a Latin word meaning "and from the Son", added by the Western church to the Nicene Creed. The original 381 AD Creed said the Holy Spirit "proceeds from the Father"; the West added "and from the Son" from around the 6th century, ratified for Rome in 1014. Orthodoxy rejects the addition on two grounds: it was made unilaterally without an ecumenical council, and it obscures the Father's role as the sole source of the Trinity. It remains a central sticking point in ecumenical dialogue.

How many Orthodox and Catholic churches are there in Australia?

The Australian Church Directory lists 2,157 Catholic parishes and 343 Orthodox churches as of July 2026. The Orthodox listings span 13 distinct jurisdictions: Greek Orthodox (139), Serbian Orthodox (44), Coptic Orthodox (42), Russian Orthodox (30), Macedonian Orthodox (26), Antiochian Orthodox (17), Indian Orthodox (8), Ethiopian and Eritrean Orthodox (5), Ukrainian Orthodox (3), Romanian Orthodox (3), Syriac Orthodox (2), Bulgarian Orthodox (1), and generic Orthodox parishes (23). Catholic is the single largest denomination in the directory; Orthodox is smaller by count but far more jurisdictionally diverse.

Which is bigger in Australia?

Catholic is much bigger. The 2021 Australian Census recorded 5,075,907 people identifying as Catholic (20.0% of Australians), versus 594,458 Eastern Orthodox (2.3%) and 111,120 Oriental Orthodox (0.4%). Catholicism is the largest religious affiliation in the country. Orthodox affiliation combined sits at about 2.8%, largely concentrated in Greek, Macedonian, Serbian, Russian, and Coptic communities in Sydney and Melbourne.

Why do Orthodox Christians often celebrate Easter on a different date to Catholics?

The two churches use different calendars to compute the Paschal date. Catholics follow the Gregorian calendar (adopted in 1582); most Orthodox jurisdictions follow the Julian calendar for feast days. When the two calculations converge, Easter is on the same Sunday; when they diverge, Orthodox Pascha falls one, four, or five weeks after Western Easter. In 2025 the dates coincide on 20 April; in most years they do not.

Do Orthodox priests marry?

Yes, with a specific rule. In Orthodoxy, a man must marry before ordination if he intends to. Once ordained a deacon or priest, marriage or remarriage is not permitted. Bishops in Orthodoxy are always drawn from the unmarried clergy — usually monks — so celibacy remains the rule at the episcopal level. Catholic priests of the Latin (Roman) Rite are required to be celibate; priests of the Eastern Catholic Rites in communion with Rome may be married, following the older Byzantine practice.

What is the difference between Eastern Orthodox and Oriental Orthodox?

They are two distinct families of churches with different Christological positions and separate historical splits. Eastern Orthodox (also called Chalcedonian Orthodox) includes the Greek, Russian, Serbian, Macedonian, Antiochian, Romanian, Bulgarian, and Ukrainian Orthodox churches, and accepts the Council of Chalcedon (451 AD). Oriental Orthodox includes the Coptic, Armenian, Ethiopian, Eritrean, Syriac (Jacobite), Indian (Malankara), and Eritrean churches, and rejects Chalcedon. The two families reunited in dialogue during the 20th century on Christology but remain out of formal communion. Both families are represented in Australia.

Are Eastern Catholic churches the same as Orthodox?

No. Eastern Catholic churches use Byzantine, Antiochene, Alexandrian, Armenian, or East Syriac liturgy — often visually indistinguishable from Orthodox worship — but they are in full communion with Rome and accept the Pope's universal jurisdiction. They are Catholic in doctrine and Eastern in worship. Australia has five Eastern Catholic eparchies: Maronite (Sydney), Melkite Greek (Sydney), Ukrainian (Melbourne), Syro-Malabar (Melbourne), and Chaldean (Sydney). By contrast, Orthodox churches are not in communion with Rome. This distinction is often missed because both groups can look identical to a visitor.

Can I find a Catholic or Orthodox church in my suburb?

Yes. The Australian Church Directory lists Catholic and Orthodox parishes across all 8 Australian states and territories, with addresses, denominations, and contact details. Browse by suburb or by denomination.

Find a local congregation

Use the directory to find a church near you:

Sources

Australian Bureau of Statistics — 2021 Census, Religious affiliation (Catholic: 5,075,907 / Eastern Orthodox: 594,458 / Oriental Orthodox: 111,120).
Australian Church Directory (auschurches.com.au), accessed July 2026 — directory counts by denomination and jurisdiction.
Australian Catholic Bishops Conference — catholic.org.au. Diocesan structure.
Catholic-Hierarchy.org — current Australian Catholic dioceses and eparchies (catholic-hierarchy.org/country/dau2.html).
CNEWA — "The Eastern Churches Down Under", ONE Magazine, on Eastern Catholic eparchies in Australia.
Greek Orthodox Archdiocese of Australia — greekorthodox.org.au.
Coptic Orthodox Diocese of Sydney and Affiliated Regions — copticorthodox.com.au.
Antiochian Orthodox Archdiocese of Australia, New Zealand and the Philippines — antiochian.org.au.
Serbian Orthodox Metropolitanate of Australia and New Zealand — spcaunz.org.
Second Vatican Council documents (Lumen Gentium, Unitatis Redintegratio) and Joint Declaration of 1965 (lifting of mutual excommunications).