One development that did have an important effect on this religious amalgam, though it was not decisive until the 4th century, was the arrival of Christianity. The tradition of the foundation of the church of Alexandria by St. Mark cannot be substantiated, but a fragment of a text of the Gospel According to John provides concrete evidence of Christianity in the Nile valley in the second quarter of the 2nd century ce. Inasmuch as Christianity remained illegal and subject to persecution until the early 4th century, Christians were reluctant to advertise themselves as such, and it is therefore difficult to know how numerous they were, especially because later pro-Christian sources may often be suspected of exaggerating the zeal and the numbers of the early Christian martyrs. But several papyri survive of the libelli—certificates in which people swore that they had performed sacrifices to Greek, Egyptian, or Roman divinities in order to prove that they were not Christians—submitted in the first official state-sponsored persecution of Christians, under the emperor Decius (ruled 249–251). By the 290s, a decade or so before the great persecution under Diocletian, a list of buildings in the sizeable town of Oxyrhynchus, some 125 miles (200 km) south of the apex of the delta, included two Christian churches, probably of the house-chapel type. Egypt’s role in the Byzantine Empire
Diocletian was the last reigning Roman emperor to visit Egypt, in 302 ce. Within about 10 years of his visit, the persecution of Christians ceased. The end of persecution had such far-reaching effects that from this point on it is necessary to think of the history of Egypt in a very different framework. No single point can be identified as the watershed between the Roman and Byzantine period, as the divide between a brighter era of peace, culture, and prosperity and a darker age, supposedly characterized by more-oppressive state machinery in the throes of decline and fall. The crucial changes occurred in the last decade of the 3rd century and the first three decades of the 4th. With the end of persecution of Christians came the restoration of the property of the church. In 313 a new system of calculating and collecting taxes was introduced, with 15-year tax cycles, called indictions, inaugurated retrospectively from the year 312. Many other important administrative changes had already taken place. In 296 the separation of the Egyptian coinage from that of the rest of the empire had come to an end when the Alexandrian mint stopped producing its tetradrachms, which had been the basis of the closed-currency system.
Byzantine Empire, 6th centuryEgypt as part of the Byzantine Empire, c. 565 ce.Encyclopædia Britannica, Inc.
One other event that had an enormous effect on the political history of Egypt was the founding of Constantinople (now Istanbul) on May 11, 330. First, Constantinople was established as an imperial capital and an eastern counterpart to Rome itself, thus undermining Alexandria’s traditional position as the first city of the Greek-speaking East. Second, it diverted the resources of Egypt away from Rome and the West. Henceforth, part of the surplus of the Egyptian grain supply, which was put at 8 million artabs (about 300 million litres) of wheat (one artab was roughly equivalent to one bushel) in an edict of the emperor Justinian of about 537 or 538, went to feed the growing population of Constantinople, and this created an important political and economic link. The cumulative effect of these changes was to knit Egypt more uniformly into the structure of the empire and to give it, once again, a central role in the political history of the Mediterranean world.
The key to understanding the importance of Egypt in that period lies in seeing how the Christian church came rapidly to dominate secular as well as religious institutions and to acquire a powerful interest and role in every political issue. The corollary of this was that the head of the Egyptian church, the patriarch of Alexandria, became the most influential figure within Egypt, as well as the person who could give the Egyptian clergy a powerful voice in the councils of the Eastern church. During the course of the 4th century, Egypt was divided for administrative purposes into a number of smaller units but the patriarchy was not, and its power thus far outweighed that of any local administrative official. Only the governors of groups of provinces (vicarii of dioceses) were equivalent, and the praetorian prefects and emperors were superior. When a patriarch of Alexandria was given civil authority as well, as happened in the case of Cyrus, the last patriarch under Byzantine rule, the combination was very powerful indeed.
The turbulent history of Egypt in the Byzantine period can largely be understood in terms of the struggles of the successive (or, after 570, coexisting) patriarchs of Alexandria to maintain their position both within their patriarchy and outside it in relation to Constantinople. What linked Egypt and the rest of the Eastern Empire was the way in which the imperial authorities, when strong (as, for instance, in the reign of Justinian), tried to control the Egyptian church from Constantinople, while at the same time assuring the capital’s food supply and, as often as not, waging wars to keep their empire intact. Conversely, when weak they failed to control the church. For the patriarchs of Alexandria, it proved impossible to secure the approval of the imperial authorities in Constantinople and at the same time maintain the support of their power base in Egypt. The two made quite different demands, and the ultimate result was a social, political, and cultural gulf between Alexandria and the rest of Egypt and between Hellenism and native Egyptian culture, which found a powerful new means of expression in Coptic Christianity. The gulf was made more emphatic after the Council of Chalcedon in 451 established the official doctrine that Christ was to be seen as existing in two natures, inseparably united. The council’s decision in effect sent the Egyptian Coptic (now Coptic Orthodox) church off on its own path of monophysitism, which centred around a firm insistence on the singularity of the nature of Christ.
Despite the debilitating effect of internal quarrels between rival churchmen, and despite the threats posed by the hostile tribes of Blemmyes and Nubade in the south (until their conversion to Christianity in the mid-6th century), emperors of Byzantium still could be threatened by the strength of Egypt if it were properly harnessed. The last striking example is the case of the emperor Phocas, a tyrant who was brought down in 609 or 610. Nicetas, the general of the future emperor Heraclius, made for Alexandria from Cyrene, intending to use Egypt as his power base and cut off Constantinople’s grain supply. By the spring of 610 Nicetas’s struggle with Bonosus, the general of Phocas, was won, and the fall of the tyrant duly followed.