Some Christian tradition suggests that St. Thomas, known as "the Apostle of India" or possibly St. Bartholomew were the first to spread the Christian gospel in China. The third century Christian writer Arnobius mentions in a text a people known as the "Seres" as being among the groups (he enumerates also the Persians and Medes) which had been evangelized at that time. While there is evidence that Christianity existed in Mesopotamia and Persia by the first century, at this time there is no extant documentation that Christianity had entered China before the Assyrian Church of the East sent a bishop there in the fifth century.
In 410 the Sassanid emperor summoned the Persian church leaders to the Synod of Seleucia. His purpose was to make the catholicos of Seleucia-Ctesiphon minority leader of his people and personally responsible for their good conduct throughout the Persian Empire.
In 424 the bishops of Persia met in council under the leadership of Catholicos Dadiso and determined that there would be no reference of their disciplinary or theological problems to any other power, especially not to any church council in the Roman Empire The formal separation from the See of Antioch and the western Syrian Church under the Byzantine Emperors, occurred at this synod in 424, seven years before the Council of Ephesus was convened.
It was the Council of Ephesus which decided the question of the title of the mother of Jesus and lead to the condemnation of Nestorius, patriarch of Constantinople, capital of the Roman Empire. The theological nicety of ‘Theotokos’ as her title rather than ‘Christotokos’, was irrelevant to the Persian Christians and those even further east. They were Greek terms, and the Persian Church used Syriac, not Greek. Plus the Assyrian Church was already autocephalous and was not bound by any decision of the Roman Empire's church councils.
Later European church historians decided to categorize the Persian Church as the “Nestorian Church”, an historically inaccurate, theologically incorrect, and heresiologically motivated pejorative. The present head of the Assyrian Church of the East, Catholicos Patriarch Mar Dinkha IV, explicitly rejected the term Nestorian, on the occasion of his consecration in 1976. Following Mar Dinkha's comments, Anglican Church leaders in 1988 publicly repudiated the use of this label for the Assyrian Church of the East.
Christianity is thought to have been introduced into China during the Tang Dynasty (618–907), but it has also been suggested that the Assyrian Patriarch of Seleucia-Ctesiphon created a metropolitan see in China in 411. It came through representatives of the Assyrian Church of the East. In China, the religion was known as Jingjiao (景教), or the Luminous Religion. They initially entered China more as traders than as professional missionaries. The Assyrians were largely of Hebrew extraction, tracing their lineage to those who did not return to Palestine following the Assyrian and Babylonian captivities. During the early centuries of Christian expansion, they considered the message of Jesus a fulfillment of their Jewish faith. Eventually, the Assyrian Christians intermarried with other Syriac-speaking peoples east of the Euphrates and spread their faith throughout Turkestan, Mongolia, China and Japan. Some records indicate that Jacobite Christians also visited China during this period, but that their impact was minimal. A stone stele (the Assyrian Christian Stele) erected at the Tang capital of Chang'an in 781 and rediscovered in February 1625 describes flourishing communities of Christians throughout China, but beyond this and few other fragmentary records relatively little more was known of their history until the late 1900s.
The Assyrian Christians met the world's largest empire at the zenith of its cultural, intellectual and administrative attainment. Tang China possessed a sophisticated religious and ethical system. Its people had long lived in an environment of religious syncretism. When Tang forces conquered Turkestan (630) and reopened the ancient trade route to the West, Alopen, an Assyrian bishop, felt the time had come to evangelize this mighty empire.
In 635 he was received by the prime minister Duke Fan Hiuen-ling, at Chang-an (Hsian-Fu), in line with the emperor's broad policy of toleration and interest in fostering foreign religions. With scholars assigned to assist him, Bishop Alopen translated the holy book into Chinese, and in July 638 the emperor graciously issued a proclamation ordering the publication and dissemination of this translation of the Holy Bible. “Let it be preached freely in our empire.”
The Sutra of Jesus the Messiah, sought to introduce the Chinese to the Christian faith and specifically pointed out that the gospel contained nothing subversive to China's ancient traditions, loyalty to the state and filial piety being of the essence of the law of Christ.
The following emperor, Kausung, was pleased to continue emperor Taitsung's policy of toleration towards Christianity. He was sufficiently pleased to permit the building of Assyrian Christian churches in every province of China, and to decree Bishop Alopen the title of “Great Conservator of Doctrine for the Protector of the Empire” (i.e., metropolitan Chang-an).
Unfazed by the challenge, the Assyrians built and staff monasteries in China's key cities. They were also quite aggressive in their proclamation of the Christian faith. They persevered in their efforts to phrase the Christian message in the philosophical language of the Confucian court in order to make it intellectually acceptable to the literati.
On 7 January 781 in the reign of Kienchung of the Tang dynasty, the Assyrian Christian Stele was erected to commemorate the diffusion of Christianity throughout China. It says, “The religion spread throughout the ten provinces....monasteries abound in a hundred cities.”
The Assyrians experienced a series of setbacks as a result of court intrigues among the Confucian bureaucrats, the jealousy of Taoist and Buddhist leaders, and the upheavals of civil war. By their medical knowledge and surgical skill the Assyrians gave a good name to their faith, but their top-heavy, non-Chinese leadership tended to lead them to be classed with Buddhism and Zoroastrianism as another “foreign religion”. Although their monasteries were self-supporting, self-governing, and self-propagating entities, Chinese clergy were only permitted to fill the lower ranks. It has been suggested this implies the Assyrians gave high priority to serving the foreign trading community. At any event, they depended largely upon its representatives for initiative and leadership.
The vitality of the Assyrian church diminished with the passage of time. The major reason was the frequent disruption of its links to its centers in Mesopotamia. In their isolation, the Assyrian Church in China absorbed more Chinese culture, to the extent that some early 20th century historians thought it had fallen prey to syncretistic tendencies. Anachronistically applying protestant thought to this ancient Church one historian also perpetuated the Nestorian misnomer saying:-
Their simplicity of faith and worship, their reverence for scripture, their abhorrence of image and picture worship, of the confessional and of the doctrine of purgatory, and their not adoring the Host in the Communion Supper constitute them the Protestants of Asia.
As for the Da-chin (Assyrian) and Muhu (Zoroastrian) temples, these heretical religions must not alone be left when the buddhists have been suppressed; they must all be compelled to return to lay life and resume their original callings and pay taxes, or if they are foreign they shall be sent back to their native places.
What began in opposition to Buddhist excesses, first among Confucian officials, was continued by a pro-Taoist emperor. Christian monks and nuns were evicted from their monasteries and forced to seek a secular living and their properties were confiscated. Books and artifacts were destroyed and leading figures — especially those of foreign extraction, whose continuing role is condemned in the decree — were forced to hide and hold underground services or to flee. Assyrian missions from Persia and Bactria in the eighth, ninth, and tenth centuries, however, strengthened the churches in some provinces, but evidence for their condition or survival throughout Tang provinces is fragmentary.
In 986 a monk reported to the Assyrian Patriarch:
"Christianity is extinct in China; the native Christians have perished in one way or another; the church has been destroyed and there is only one Christian left in the land".
This was an overstatement, for the Assyrian Church continued to flourish throughout Central Asia well into the fourteenth century among the northern tribes, such as Uyghurs, Turks, and Mongols. However, the record of the closing years of the Assyrians in China is replete with references to necrology, a Chinese-influenced practice not found in classical Christianity.
Under the emperors of the Yuan Dynasty Assyrian Christianity once again gained a foothold in China. Yet the centralizing policies of the Ming emperors meant that all things foreign were suspect, so Christianity was once again forced to go underground. The last known monument referring to Assyrian Christianity in China seems to be one dating to c. 1365 and found at Sanpen Mountain (三盆山) outside Chechang village near Zhoukoudian in the Fangshan District of Beijing. The monument relates the story of a Buddhist monk who visited the site of an old Christian monument and had a vision of a luminous cross.
The Assyrian presence in China was contingent upon retaining the favor of the Chinese Imperial Court. This made the Assyrians vulnerable when the traditional power of the Confucian scholars influenced the court to eliminate all foreigners and their religions. Also, their accumulation of land for monasteries and for the support of agricultural operations made them appear to the authorities as a state within a state, diverting people from their economic and political responsibilities to the Tang authorities. Naturally, this was also resented.
In February 1625 the Assyrian Christian Stele was found in Xian not far from His-an-fu. It is a quarried 2 ton granite slab on which the story of the Assyrian missionaries coming to China was written in both Chinese and Syriac. This discovery was of great importance to the Jesuits in China at the time, because it proved that Christianity was part of China's past and not a recent foreign incursion, thus giving support to Christians against those who were again calling for the religion to be banned.
Dozens of Jingjiao texts have survived. Some of them are translations of biblical scriptures, including the Pentateuch (牟世法王经) - Genesis is known as 浑元经, Psalms (多惠圣王经), the Gospels (阿思翟利容经), Acts of the Apostles (传代经) and the Pauline epistles (宝路法王经).