While all the ancient churches traditionally trace their roots back to one of the Apostles — or one of the 72 disciples who are mentioned without names in Luke’s Gospel — it is often difficult to verify these traditions in way which would be acceptable to modern historians.
The New Testament offers little help. It has Peter traveling to Antioch, although there is no mention in the Bible that Peter went to Rome. We also know from Acts 8:4-8 that Philip, one of the Twelve Apostles, travelled and preached in Samaria, which was not far from Jerusalem. There is more evidence in the Bible about Paul desiring to go to Rome and ultimately going there as a prisoner. Paul is also known to have founded several churches. However, although he insists that he is an “apostle” (cf. 1 Corinthians 15:9 and elsewhere), Paul was not a member of the original Twelve Apostles.
While traditions about the apostolic origins of some churches may be hard to verify, they do have deep roots. Early on, traditions arose according to which of the Twelve evangelized a particular area — Thomas in India, Andrew in Byzantium, and so on.
Nearly 200 years later, we find — as in India and parts of Armenia — that church institutions developed. The traditions were beginning to flourish. Shrines and memorials recording the presence of one of the Twelve, even many decades later, also indicate a longer tradition. So, when churches trace their roots back to apostolic times, there is very often an historical core to those traditions.
But before long, several forces — mostly political, theological, linguistic and cultural — led to isolation between the churches of the East and those of the Latin and Greek-speaking West.
The Church of the East, sometimes inaccurately called the Nestorian Church, was a church separated from the Western churches in many ways. First, it existed politically in the Persian Empire, which was almost in a constant state of war with Byzantium, the political center of Western Christianity. Secondly, its theology found the councils of Ephesus and Chalcedon unacceptable. This actually was to its advantage because “orthodox” Christianity was — sometimes correctly — seen by the Persians as the faith of the Byzantine enemies. Lastly, members of the Church of the East spoke Syriac and different dialects of Aramaic, in contrast to the Greek and Latin of the churches in the West.
But it was, in many ways, ahead of its time. It might surprise people to learn that the Church of the East developed schools of theology in Edessa and Nisibis (both in modern Turkey) some 500 years before the opening of the first great European universities. Also, for the first five centuries of the church, most Christians lived east of the Mediterranean; by the time of the Muslim conquests in the mid-seventh century, Christians formed a slight majority of the population of the Persian Empire.
One reason for its growth is that the Church of the East was renowned for its missionary activities. By the eighth century it had metropolitan sees (archdioceses) in several places in China and across Central Asia. The Church of the East brought Christianity to China before it arrived in Denmark and the Slavic countries of Europe and almost 1,000 years before St. Francis Xavier arrived in the region.
Although the Church of the East remains widely unknown in the West, for centuries it was one of the most vital forces for theology and missionary activity in the Christian world.
Related:
2,000 Years of Christianity in Syria and Mesopotamia — Introduction