Traditions
A

Tradition · Church of the East

Assyrian Church of the East

FollowersNo verified countworkbook figure is unsourcedHow countedSynod of Seleucia-Ctesiphon410Bishops in the Persian Empire received the Creed of Nicaea. Separation from the churches of the Roman Empire came gradually; the church never received Ephesus (431).Read the historyCompare with another tradition

Heir of the ancient church of Mesopotamia and Persia, which once reached China.

Relationships with other traditions

How it took shape

Since then

Key timeline

View full timeline (6)
  1. 410

    Synod of Seleucia-Ctesiphon

    Organises the church in the Persian Empire under a catholicos.

  2. 431

    Council of Ephesus

    Condemns Nestorius and affirms Mary as Theotokos. The Church of the East never received this council.

  3. 1994

    Common Christological Declaration

    Signed with the Catholic Church, recognising a shared faith in Christ despite different formulations.

Classification
Church of the East. Developed in the Persian Empire; it rejects the label “Nestorian”, which it regards as misleading.
What this entry covers
A self-governing church within a wider family. The Assyrian Church of the East, principal heir of the East Syriac Church of the East. The Ancient Church of the East (separate since 1968) and the Chaldean Catholic Church (an Eastern Catholic church) share its heritage.
Synod of Seleucia-Ctesiphon
410. Bishops in the Persian Empire received the Creed of Nicaea. Separation from the churches of the Roman Empire came gradually; the church never received Ephesus (431).

Relationships with other traditions

Gradual estrangement410–7th centuryA gradual process

A church beyond the Roman Empire

Assyrian Church of the EastCatholic ChurchEastern Orthodox churchesOriental Orthodox churches · the churches of the Roman Empire

Gradual estrangement: Churches grow apart over a long period without a single act of separation. Any date given is a convenient marker, not a moment of division.

The Church of the East grew up in the Persian Empire. A synod at Seleucia-Ctesiphon in 410 received the Creed of Nicaea; synods in 420 and 424 followed, and the church came to govern itself under its catholicos. It never received the Council of Ephesus (431), but its separation was a gradual development rather than a single schism at Ephesus.
3 sources

Provisional: broadly supported, but awaiting fuller checking.

What changed
Later developments

Compare Assyrian Church of the East and Catholic ChurchCompare Assyrian Church of the East and Eastern Orthodox ChurchCompare Assyrian Church of the East and Coptic Orthodox ChurchCompare Assyrian Church of the East and Ethiopian Orthodox Tewahedo Church

Reconciliation1994–2001

Catholic–Assyrian reconciliation

Catholic ChurchAssyrian Church of the East

Reconciliation: A formal act of reconciliation, such as lifting condemnations or asking forgiveness. It does not by itself restore communion.

The 1994 Common Christological Declaration recognised a shared faith in Christ despite different formulations; in 2001 the Catholic Church accepted the Anaphora of Addai and Mari as valid and allowed mutual admission to the Eucharist with Chaldean Catholics in cases of necessity.
2 sources
Later developments
  • 2017: the joint committee signed a Common Statement on 'Sacramental Life'. It does not restore full communion or permit concelebration; the next phase concerns the constitution of the Church.
    Source
Today as of October 2026

Separate, in formal dialogue

Not in full communion. After the 2017 statement on sacramental life, the joint committee's next phase concerns the constitution of the Church; Chaldean Catholics and Assyrians may share the Eucharist in cases of necessity.
2 sources

Agreement recordAgreement recordAgreement recordCompare Assyrian Church of the East and Catholic Church

Ecclesial union16th–17th centuriesA gradual process

The Chaldean union with Rome

Eastern Catholic Churches (Chaldean Catholic Church)Assyrian Church of the East

Ecclesial union: Part of one church enters communion with another while keeping its own liturgy, hierarchy and law.

Part of the Church of the East entered communion with Rome in the 16th and 17th centuries, forming what became the Chaldean Catholic Church; the two churches share the East Syriac liturgical heritage.
2 sources

Provisional: broadly supported, but awaiting fuller checking.

Later developments
Today as of October 2026

Separate, in formal dialogue

Separate churches with limited pastoral sharing of the Eucharist in cases of necessity.
Source

Agreement recordCompare Assyrian Church of the East and Eastern Catholic Churches

Full timeline

  1. 410

    Synod of Seleucia-Ctesiphon

    Organises the church in the Persian Empire under a catholicos.

    Explained below: A church beyond the Roman Empire

  2. 424

    Synod of Markabta

    Declares the catholicos answerable to no Western patriarch.

  3. 431

    Council of Ephesus

    Condemns Nestorius and affirms Mary as Theotokos. The Church of the East never received this council.

    Explained below: A church beyond the Roman Empire

  4. 635

    Mission to China

    The Xi’an Stele (781) records the arrival of the monk Alopen at the Tang court in 635.

  5. 1994

    Common Christological Declaration

    Signed with the Catholic Church, recognising a shared faith in Christ despite different formulations.

    Explained below: Catholic–Assyrian reconciliation

  6. 2001

    Guidelines on Addai and Mari

    The Catholic Church accepts the Anaphora of Addai and Mari as valid and allows Assyrian and Chaldean faithful to receive the Eucharist in each other’s churches in cases of necessity.

    Explained below: Catholic–Assyrian reconciliation

Positions used in comparisons

Short, sourced statements that the Atlas compares across traditions. Where a tradition has no single teaching authority, the record says whose statement it follows.

Christ
Christ is true God and true man; East Syriac theology speaks of two natures (kyane) and two qnome in one person (parsopa). Qnoma is not the same as 'person', and the 'two persons' charge does not match the church's own texts.
2 sources
Creeds and councils
Received the Creed of Nicaea at the Synod of 410; does not receive the Council of Ephesus (431).
Source
Sacraments and ordinances
Its Eucharist includes the ancient Anaphora of Addai and Mari, which the Catholic Church accepted as valid in 2001. Its official list of sacraments (adopted 2001) follows Mar Abdisho and includes the Sign of the Cross and the Holy Leaven.
2 sources
Church and ministry
Led by its Catholicos-Patriarch, with bishops and priests in apostolic succession.
2 sources
Mary and the saints
Mary is honoured as 'the Mother of Christ our God and Saviour'; in 1994 the Catholic Church recognised this as a legitimate expression of the same faith as 'Mother of God'.
Source

Compare these positions with another tradition

The follower figure

No verified count workbook figure is unsourced

What is counted
No verified count
As of
—
Reported by
—
Type
No verified figure
Coverage
Iraq, Iran, Syria and a dispersed diaspora.
This entry is
A self-governing church within a wider family. The Assyrian Church of the East, principal heir of the East Syriac Church of the East. The Ancient Church of the East (separate since 1968) and the Chaldean Catholic Church (an Eastern Catholic church) share its heritage.
This build found no dated, sourced count; the church's own website gives no figure. The workbook gives 500,000 without a source, and community displacement makes estimates especially uncertain.
Awaiting verificationWhy?

No sufficient source has been found yet.

Replaces the starting figure. Workbook: 500,000 (no source or date).

Figures from different traditions measure different things and must not be added together or ranked against each other.

About the image · Editorial placeholder

Editorial initial. No emblem has been selected.

Editorial status

Editorial draft. Built from the starting workbook with editorial corrections and framing. It has not yet been checked against independent sources.

References

  • Workbook linkNot yet checked

    news.assyrianchurch.org

    Link supplied in the source workbook (“Christian Denominations”, row 17). It has not been checked to confirm that it supports every claim in that row.

Original workbook record

Imported unchanged from “Christian Denominations”, row 17. Values here are the starting dataset, not verified facts; where the Atlas differs, the reason is noted below.

Denomination / Tradition
Assyrian Church of the East
Broader Tradition
Church of the East
Date Established / Split
431 AD
Origin / Location
Mesopotamia / Erbil, Iraq
Forming Event / Schism
Council of Ephesus Schism
Approx. Practitioners
500,000
Broke Away From
Unified Early Church
Primary Reason for Split / Core Doctrine
Rejection of the Council of Ephesus and the title 'Theotokos' (Mother of God) for Mary, upholding traditional East Syrian Christology.
Reference / Information Link
https://news.assyrianchurch.org

Editorial notes on this record

  • Primary Reason for Split / Core Doctrine: Workbook says the church rejects “the title Theotokos”. Broadly right, but the church describes this as preferring “Mother of Christ”. Reworded carefully.
  • Approx. Practitioners: 500,000 has no source or date; there was a separate “Ancient Church of the East” after 1968.
  • Date Established / Split: v0.1 used “Ephesian division · 431” as the primary event. v0.2 uses the Synod of Seleucia-Ctesiphon (410) and explains the separation as gradual (Brock 1985). See correction C-04.

Research sources for this entry

Every relationship, position and figure above cites these. Each links to the Atlas’s single source register, which shows what each source supports and whether it was read.