The intricate details of Christian missions to Sudan in the 6th century show that the only goal of their organizers was to overcome their Monophysite (and, vice versa, Chalcedonite) competitors. Emperor Justinian and his wife Theodora, who supported rival religious parties, sent missions to Sudan racing one another (as is brilliantly described by John of Ephesos) and their primary goal was to persuade «barbarians» to turn down rival preachers. The only success of Constantinopolitan imperial missions to Africa was the temporary conversion of the Sudanese princedom of Makurrah to Chalcedonian creed. This princedom must be accredited as the only state outside historical boundaries of the Roman Empire which embraced Byzantine Christianity — except Rus’. Whereas the religious influence of Byzantium on Africa was meagre, its political image remained important there for five hundred years after Egypt had been conquered by Islam and all ties with it had been broken. For example, Nubian officials named themselves with Byzantine titles.
Imperial Byzantine mission made some progress in converting Persian aristocracy by the end of the 6th century. Our sources on this matter are numerous, both Persian and Latin, narrative and fabulous. If we bring them all together and single out the historical core, we will see that this short‑lived success was the result of a typical political intrigue and did not involve active preaching. The first quarter of the 7th century witnessed impressive victories of emperor Heraclius in the Middle East and considerable spread of Byzantine Christianity — but it resembled a Crusade rather than a mission. Byzantines initiated the concept of «holy war», and all the conversions were made by force (a little later strong disgust at Greeks and their religion facilitated mass conversion to Islam in the Middle East). More interesting to us is the peaceful success among Christian princes of the Caucasus and Azerbaijan: as in Africa, political appeal of the Empire turns out to be more significant than the religious one.
The propagation of Christianity in India, Central Asia and China was carried out by Nestorian missionaries who had nothing in common with Byzantium and were regarded as heretics by the imperial church. Arabic Christianity had no Greek roots, but when persecutions began, local Christians turned to Constantinople for help. Interestingly, Byzantium did not intervene but asked the Ethiopian king to do so. The source to which the author pays special attention is Vita of St. Grigentius, apostle of Himyarites (Southern Arabians). This text is of later origin, but it reflects some genuine facts and some general ideas, spread among Byzantines, of what a missionary should be like.
Summing up, the Early Byzantine period witnessed the birth of a very special kind of mission: very rarely it was the initiative of individuals or groups of monks or even local churches — usually it was a political undertaking carried out by government envoys of religious character. In most cases, such missions were invited by «barbaric» rulers, who visited Constantinople personally and got baptism at the hands of the Emperor. Leaders of primordial «barbaric states» regarded Christianity as a pass to the community of «normal» states, whereas developed political entities tried to reject the excessive Byzantine claims of global tutelage. If we outline all the missionary endeavors of Constantinople implemented outside the imperial borders without any provoking instigation from outside, we will see that they extended to the Crimea, Abkhazia, and Sudan, that is, territories which could be regarded as potential fields of political conquest.
Middle Byzantine period began with catastrophic defeats of the Empire both in Asia (from Arabs) and in Europe (from Bulgars). Greek Christianity outside Byzantium declined as well. But even before the Empire began to recover, Byzantines resumed missionary efforts. There was even more space for individual initiative than before. The first preacher of the new epoch was Stephen (8th C.), bishop of Sugdaia in the Crimea, which belonged to Khazars. Stephen was ardently christianizing Khazars on his own account, without any support from Constantinople, governed by an iconoclastic emperor hostile to Stephen. However, the real revitalization of mission came with the general renaissance of the Empire in the 9th century. This renewed interest in mission can be traced in the renewal of the cult of St. Andrew, proverbial preacher to «barbarians». His new Vita, which was written in the 1 half of the 9lh century, depicts an ideal missionary. The pivot of this trend is the appearance of Cyril and Methodius, «apostles» of Slavs. Hundreds of books were written about them and the author has no intention to go into any details. What is important is that Thessaloniki brothers mattered more to their converts than to the Empire. Constantinople did not care about the fates of the brothers, did not help them — here lies the reason why Byzantine sources never mentioned Cyril and Methodius.
The conversion of Bulgaria in the 860s already bears all the birthmarks of the «political mission run by the state», known to us from Early Byzantium. Greeks’ conduct was so unscrupulous, the spiritual instruction was so ruthlessly superseded with the imposition of Greek customs and habits, the religious aspect was so strongly overshadowed by the political one, that Bulgars abhorred it and for a short while defected to the side of Rome. Thanks to this, we have a precious source — questions put by Bulgars to the Pope concerning the missionary practice of the Byzantines. From this document we learn how inflexible and arrogant Greek missionaries were. And we know that it nearly cost them a defeat. The responses of the Pope Nicholas I to these questions show drastic differences between Western and Eastern approaches to mission. By the way, the same intransigence was shown by Methodius and his disciples in Moravia. The final defeat of Cyrillo‑Methodian mission there (not backed by Byzantine government anyway) was caused by the narrow‑minded position of the Orthodox clergy, who did not condescend to the immaturity of Moravian Christianity and demanded from Slavic neophytes to observe the most severe Byzantine rites. On the other hand, competing Latin clergy showed a great deal of tolerance and won the upper hand. The same period saw the first attempt to baptize Rus’ — most probably, abortive. Patriarch Photius, a great literatus and churchman of the 9th century, who is believed to be the mastermind of Byzantine missionary efforts of this period, shows great contempt for «barbarians». From his point of view, the only way for them to become Christians was to bow to the Christian Empire.
It was a deadlock for mission: in order to convince people in whatever, you have to please them. Byzantines learned their lesson: it becomes obvious from our scrutiny of another crucial source, insufficiently used by scholars in this respect — letters of Constantinopolitan Patriarch Nicholas Mysticos (1 half of the 10th C.). He instructs his missionaries to make tactical concessions to «barbaric» rulers — quite opposite to what Patriarch Photios insisted on in the previous century. The first success of the 10th century was the conversion of Alania in the Northern Caucasus. Although it turned out to be not decisive and Alanian Christianity was uprooted soon for several decades, although a great role in this conversion was played by Abkhazian Orthodox church (a replay of the situation of Arabia — Ethiopia in the 6th C.), still it is hard to overestimate the fact that Constantinopolitan Patriarchate finally won over this, absolutely «barbaric» area for itself for the next five hundred years.