Nestorianism
The Church of the East is associated with Nestorianism, a Christological doctrine advanced by Nestorius, Patriarch of Constantinople from 428 – 431, which emphasizes the disunion between the human and divine natures of Jesus.
Nestorius's doctrine represented the culmination of a philosophical current developed by scholars at the School of Antioch, most notably Nestorius's mentor Theodore of Mopsuestia. This became a source of controversy when Nestorius publicly challenged usage of the title Theotokos (literally, "Bearer of God") for the Virgin Mary. He suggested that the title denied Christ's full humanity, arguing instead that Jesus had two loosely joined natures, the divine Logos and the human Jesus, and proposed Christotokos (literally, "Bearer of the Christ") as a more suitable alternative title. These statements drew criticism from other prominent churchmen, particularly from Cyril, Patriarch of Alexandria, leading to the First Council of Ephesus in 431, which condemned Nestorius for heresy and deposed him as patriarch. Nestorianism was officially anathematized, a ruling reiterated at the Council of Chalcedon in 451. However, a number of churches, particularly those associated with the School of Edessa in Mesopotamia, supported Nestorius—though not necessarily the doctrine ascribed to him—and broke with the churches of the Roman Empire. Many of Nestorius' supporters relocated to Sassanid Persia. These events are known as the Nestorian Schism.
Although the "Nestorian" label was initially a theological one, applied to followers of the Nestorian doctrine, it was soon applied to all associated churches with little regard for theological consideration. While often used disparagingly in the West to emphasize the Church of the East's connections to a heretical doctrine, many writers of the Middle Ages and since have simply used the label descriptively, as a neutral and conventional term for the church. Other names for the church include "Persian Church", "Syriac" or "Syrian" (often distinguished as East Syriac/Syrian), and, more recently, "Assyrian".
In modern times some scholars have sought to avoid the Nestorian label, preferring "Church of the East" or one of the other alternatives. This is due both to the term's derogatory connotations, and because it implies a stronger connection to Nestorian doctrine than may have historically existed. As Wilhelm Baum and Dietmar W. Winkler said, "Nestorius himself was no Nestorian" in terms of doctrine. Even from the beginning, not all churches called "Nestorian" adhered to the Nestorian doctrine; in China, it has been noted that none of the various sources for the local Nestorian church refer to Christ as having two natures. As such, in 2006 an academic conference changed its name from "Research on Nestorianism in China", explaining in the Preface, "...it was decided not to keep the term "Nestorianism" in the title of the future conferences and the present book, but to use the term Church of the East, which is correct and wide enough to cover the whole field of the research."
The 2000 work, The Ecclesiastical Organisation of the Church of the East, 1318–1913, offers an explanation in the first chapter:
The terminology used in this study deserves a word of explanation. Until recently the Church of the East was usually called the 'Nestorian' church, and East Syrian Christians were either 'Nestorians' or (for the Catholic group after the schism of 1552) 'Chaldeans'. During the period covered in this study, the word 'Nestorian' was used both as a term of abuse by those who disapproved of the traditional East Syrian theology, as a term of pride by many of its defenders (including Abdisho of Nisibis in 1318, the Mosul patriarch Eliya X Yohannan Marogin in 1672, and the Qudshanis patriarch Shem'on XVII Abraham in 1842), and as a neutral and convenient descriptive term by others. Nowadays it is generally felt that the term carries a stigma, and students of the Church of the East are advised to avoid its use. In this thesis the theologically neutral adjective 'East Syrian' has been used wherever possible, and the term 'traditionalist' to distinguish the non-Catholic branch of the Church of the East after the schism of 1552. The modern term 'Assyrian', often used in the same sense, was unknown for most of the period covered in this study, and has been avoided.
The modern Assyrian Church of the East has shunned the "Nestorian" label. The church's present head, Catholicos-Patriarch Mar Dinkha IV, explicitly rejected the term on the occasion of his consecration in 1976.
Read more about this topic: Persian Church