Our History

The Holy Apostolic Catholic Church of the East is one of the most ancient Christian communities in the world, founded in the earliest days of Christianity and rooted in the apostolic mission of Mar Toma (St. Thomas), Mar Addai, and Mar Mari. Its heritage is deeply connected to the lands of Mesopotamia, where the Gospel first took root among Aramaic-speaking peoples.

From the beginning, the Church of the East proclaimed Christ in the Semitic language of Aramaic, the language spoken by our Lord Himself. This shared linguistic and cultural heritage helped the Christian faith spread rapidly among the Assyrians and throughout Mesopotamia, Persia, and as far as India and China.

Origins and Apostolic Foundation

The Church traces its origins to the Apostles. In his first epistle written from Babylon, St. Peter refers to "she who is in Babylon, elect together with you" (1 Peter 5:13), marking an early testament to the apostolic presence in the East.

King Abgar V (Ukkama) of Urhai (Edessa) famously sent word to Jesus Christ. This event is preserved in the Doctrine of Addai and recorded by Eusebius of Caesarea in his Ecclesiastical History, where he notes seeing the archive documents in Urhai. Following the Ascension, Mar Addai was sent to Urhai, healing the king and laying the foundations of Christian life and literature in the East.

The Apostles and their disciples carried forward this divine mission:

• Mar Toma (St. Thomas): Preached in Assyria and established Christian communities across India.
• Mar Addai: Evangelized Mesopotamia and the surrounding Persian regions.
• Mar Mari: Disciple of Mar Addai, established churches across Babylonia and Seleucia-Ctesiphon.

The lineage of early leadership in the See of Seleucia-Ctesiphon includes:

1. Mar Addai (c. 33–45 A.D.)
2. Mar Agai (c. 45–48 A.D.)
3. Mar Mari (c. 48–81 A.D.)
4. Mar Abris (c. 82–98 A.D.)

Over two millennia, a line of Patriarchs has occupied the Patriarchal See of the Church of the East.

The Patriarchal See

The Patriarchal See was originally established in Seleucia-Ctesiphon, the ancient capital of the Persian Empire. Following historical political shifts, the See was transferred to Baghdad during the Abbasid Caliphate.

Today, the Church continues in uninterrupted apostolic succession under the leadership of its Catholicos-Patriarch.

On June 9, 2023, His Holiness Mar Gewargis III Younan was consecrated as the 110th Catholicos-Patriarch of the Ancient Church of the East at the Cathedral of St. Mary in Baghdad. His Holiness faithfully carries forward the ancient mission of shepherding the faithful, preserving the apostolic tradition, and guiding the Church in unity, holiness, and truth.

Growth and Mission

By the late 1st century A.D., early Christian communities were established stretching from Mesopotamia to the Caspian Sea. The missionary spirit of the Church of the East led to vast expansion across the Middle East, Persia, Central Asia, India, and China—where the Nestorian Stele of Xi'an (erected in 781 A.D.) stands as historic proof of its early presence.

Doctrine and Teaching

The Church of the East teaches that Jesus Christ is true God and true Man, acknowledging two natures (kyane) and two individual existences (q'nume) united in the one Person (parsopa) of the Son of God.

• Q'noma (q'nōmā): The Aramaic theological term describing an individual, concrete reality or essence through which a nature (kyana) is realized.
• Yaldath Mshikha (Mother of Christ): The Church emphasizes the historical title Yaldath Mshikha (Bearer/Mother of Christ) rather than Yaldath Alaha (Bearer/Mother of God) to safeguard both the distinct divinity and humanity of