Persian Church - Parthian and Sassanid Periods

Parthian and Sassanid Periods

Christians were already forming communities in Mesopotamia as early as the first century, when it was part of the Parthian Empire. By the third century, the area had been conquered by the Persian Sassanid Empire (becoming the province of Asuristan), and there were significant Christian communities in northern Mesopotamia, Elam, and Fars. The Church of the East traced its origins ultimately to the evangelical activity of the apostles Addai, Mari and Thomas, but leadership and structure was disorganized until the establishment of the diocese of Seleucia-Ctesiphon, the bishop of which came to be recognized as Catholicos, or universal leader, of the church. This position received an additional title later, Patriarch of the East.

These early Christian communities were reinforced in the fourth and fifth centuries by large-scale deportations of Christians from the eastern Roman Empire. However, the Persian Church faced several severe persecutions, notably during the reign of Shapur II (339–79), from the Zoroastrian majority who accused it of Roman leanings. The church grew considerably during the Sassanid period, but the pressure of persecution led to the Persian Church declaring itself independent of all other Christian churches in 424.

Meanwhile, in the Roman Empire, the Nestorian Schism had led many of Nestorius' supporters to relocate to the Persian Empire. The Persian Church increasingly aligned itself with the Nestorian schismatics, a measure encouraged by the Zoroastrian ruling class. The church became increasingly Nestorian in doctrine over the next decades, furthering the divide between Roman Christendom and the Nestorians. In 486 the Metropolitan of Nisibis, Barsauma, publicly accepted Nestorius' mentor, Theodore of Mopsuestia, as a spiritual authority. In 489, when the School of Edessa in Mesopotamia was closed by Byzantine Emperor Zeno for its Nestorian teachings, the school relocated to its original home of Nisibis, becoming again the School of Nisibis, leading to a wave of Nestorian immigration into the Persian Empire. The Persian patriarch Mar Babai I (497–502) reiterated and expanded upon his predecessors' esteem for Theodore, solidifying the church's adoption of Nestorianism.

Now firmly established in the Persia, with centers in Nisibis, Ctesiphon, and Gundeshapur, and several metropolitan sees, the Church of the East began to branch out beyond the Persian Sassanid Empire. However, through the 6th century the church was frequently beset with internal strife and persecution from the Zoroastrians. The infighting led to a schism, which lasted from 521 until around 539, when the issues were resolved. However, immediately afterward Roman-Persian conflict led to a renewed persecution of the church by the Sassanid King Khosrau I; this ended in 545. The church survived these trials under the guidance of Patriarch Mar Abba I, who had converted to Christianity from Zoroastrianism.

By the end of the 5th century and the middle of the 6th, the area occupied by Nestorians included "all the countries to the east and those immediately to the west of the Euphrates", including Persia, Egypt, Syria, Arabia, Socotra, Mesopotamia (Assyria and Babylonia), Media, Bactria, Hyrcania, and India; and possibly also to places called Calliana, Male, and Sielediva (Ceylon). Beneath the Patriarch in the hierarchy were nine metropolitans, and clergy were recorded among the Huns, in Persarmenia, Media, and the island of Dioscoris in the Indian Ocean.