What would have become of Christianity without Constantine? In the following I will presuppose that Constantine’s influence on early Church was both vital and far-reaching, and that a similar man would not have emerged later on.
It is generally accepted fact that the accession of Constantine was a turning point in the history of the Christian church and considered the beginning of the Christendom. Constantine took a role of patronus to his adopted religion. He granted privileges for the Christian clergy (exemption from taxes), promoted them to high offices, endowed them with imperial lands and wealth, had an extraordinary number of basilicas built while withdrawing support from traditional pagan cults. In a nutshell, he raised Christian church from obscurity into position of power, to which it would cling in suprising tenacity.
Constantine abolished crucifixion and tried to eliminate gladiatorial games, but most importantly, he used his autocratic powers to enforce orthodoxy where none had existed. There were even implications abroad. As long as Romans had persecuted Christians, Sassanid Perians had usually tolerated theirs, for political reasons. After Constantine’s conversion, Christians in Persia were regarded as enemy spies. But if Constantine had been defeated at Saxa Rubra, none of this would have happened. Christianity would have remained popular if discordant religion among the poor and uneducated, but the vital actors of the Roman state – its military-industrial complex and upper classes – would have remained unmoved.
Pauline Church divided
The Post-Apostolic era was extremely diverse both in terms of beliefs and practices. With staunch polytheists like Maxentius and Maximinus Daia in power, the Pauline church remained schismatic. Patriarchs of Alexandria, caretakers of Rome’s biggest Christian congregation, tried to assert themselves as leaders of the whole Christendom, and started calling themselves as popes of the Holy See of St. Mark. They were met with marked disdain. In North Africa they were rebutted by puritan Donatists, Novatianists, called καθαροι (“katharoi”), and Tertullianists, who believed in the ecstatic prophesies of Montanus. To make things worse, competing churches, e.g. Church of Marcion and Valentinian Gnostic sects, profited from the lack of orthodoxy and unified leadership.
In 321 CE emperor Maximinus Daia ordered all Christian writings to be burned and all Christian churches to be deprived of their properties. It was largest and best organised persecution Romans had yet witnessed. Many Christians fled to the countryside, especially in Egypt, where they formed monastic communities. Others migrated further south and east, to Persia and India, where Thomas the Apostle had already established his own church. Silvester, bishop of Rome, was exiled to Sicily when he refused to show his loyalty to the emperor. Maxentius replaced him with Felix, young and moderate theologian who was willing to reconcile Church with Roman law and custom. To many hard-liner Christians it amounted to near apostasy, and the bishopric of Rome lost much of its prestige and influence as a consequence. Few years later, Church of Egypt was split between followers of Arius and trinitarian Athanasius, and the division was complete.
Ex oriente lux
As early as the 1st and 2nd centuries, Jewish and Christian communities existed in the regions of Assyria, Babylonia, and Persia. Their numbers were greatly increased by Christian immigration from Rome. One of the most famous Persian Church fathers was dalmatian priest Eusebius Sophronius Hieronymys, who was exiled from Rome in 382 and settled down in Seleucia-Ctesiphon, capital of the Sassanid Empire (Ērānshahr), where he would translate the Bible into Persian. A turning point came in the fifth century, when Shah Yazdegerd I authorised Christians as a legal sect in Zoroastrian Persia. The Council of Seleucia-Ctesiphon met in 410 to establish the Apostolic Catholic Assyrian Church and select a formal Catholicos, or leader. The Catholicos, Mar Isaac, was both to lead the Christian community, and be aswerable for it to the Shah.
Persians were eager to profit from the religious problems of their eternal enemy. Yazdegerd even took bishops as his councelors and punished nobles and Zoroastrian priests who persecuted Christians. Christian Catechetical school was opened in Gundeshapur to lure scholars and encourage further emigration, and the Assyrian church grew considerably. Shah Bahram V (421–438) declared himself as protector of Christians when he declared war on Rome, in attempt to arouse Rome’s Christian subjects to rebellion. In 431 he supported the Nestorian schism, by granting protection to Nestorians, executing Catholicos Babowai, and replacing him with the Nestorian Bishop of Nisibis, Barsauma. Catholicos Mar Babai I (497-503) solidified the association of the Assyrian Church with Nestorianism.
Now firmly established in Persia, with centers in Edessa, Nisibis, Ctesiphon, and Gundeshapur, the Assyrian Church began to breach out beyond the Persian Empire. Nestorian missionaries established dioceses in the Arabian Peninsula and India, entered Central Asia and had significant success converting local Tatar tribes. By the end of the 6th century, Assyrian Christianity had gained a multitude of converts from local Zoroastrians and Manicheans, and dominated Persia, Armenia, Media, Chaldea, Bactria and Hyrcania, as well as Ceylon and Kerala in India . There were even bishops among the Huns. But even greater turning point was at hand. In 635, Persian cleric named Alopen introduced Christianity to China.
Coptic and Hellenic Christians
Archibishop of Guang and the Luminous religion