These Christological commitments and debates imply a conception of the relationship between God and man, a theology of "participation" which, thanks to the creative synthesis of Maximus the Confessor, would serve as the backbone of the entire development of Byzantine Christian thought, up to the conquest of Constantinople by the Turks. Thus, there is an essential continuity between the patristic era and late Byzantine theology, as we intend to show in this study, and it embraces almost a whole millennium of Christian history in the East: from the Council of Chalcedon to the fall of Constantinople.

This continuity, however, does not manifest itself in any formal authority or model that would be recognized by everyone throughout the entire period indicated above. Rather, it consists in the consistency of the theological way of thinking, in the consistency of the understanding of human destiny in relation to God and the world. "God became man," writes Athanasius, "so that man could become God." This fundamental assertion of Alexandrian theology, which dominated all theological discourse on "deification," gave rise to many problems. Pantheism, flight from history, Platonic spiritualism carry obvious threats, and orthodox Chalcedonian theology as a whole is aware of them, implying a positive conception of man as a being called upon to constantly overcome his own created limitations. True human nature is not supposed to be "autocratic," but destined to participate in the divine life attainable in Christ. According to this concept, the purpose of man in the created world can be fulfilled only if the "image" of God, which originally constitutes part of human nature itself, is preserved without damage.

From the Christological controversies of the fifth century to the debates about the "essence" and "energy" of God that took place in the fourteenth century, all the major crises of Byzantine theological thought can be reduced to one or another aspect of this fundamental Christian question. Authors as diverse as Leontius of Jerusalem and Gregory Palamas, Maximus the Confessor and Symeon the New Theologian, Photius and Nicholas Cabasilas agree on the most basic points, as is easy to discover. It is this agreement that distinguishes Byzantine theology, considered as a whole, from the post-Augustinian and scholastic West, and therefore it becomes possible to attempt to offer a systematic exposition of Byzantine Christian thought, which we undertake in the second part of this work.

2. Living Tradition

It is very difficult to compose an exposition of this kind because of the very nature of Byzantine church life as reflected in theological literature. In the Byzantine era, as in the patristic era, neither councils nor theologians showed much interest in building positive theological systems. With very few exceptions, such as the Chalcedonian definition, the conciliar decrees themselves took the form of negations; they condemned the distortions of Christian Truth rather than tried to reveal its positive content – for it was perceived as a living Tradition and as an integral Truth, which is outside and above the doctrinal formula. Most theological writings are either exegetical or polemical, and in both cases the Christian faith is accepted as a given reality that can be interpreted or defended, but which does not need exhaustive formulations. Even John of Damascus, sometimes called "Aquinas of the East" for compiling a systematic "Exact Exposition of the Orthodox Faith" (De fide orthodoxa), in fact created only a brief manual, but not a theological system; and if his thought lacked something, it was precisely that originality of philosophical creativity, without which there is no new system.

A lack of concern with systematization, however, does not mean a lack of interest in the true content of the faith or an inability to create precise theological definitions. Quite the opposite. There has been no other civilization that has experienced more discussions about the adequacy or inadequacy of words expressing religious truths. The difference between homoousion and homoiousion is "of two natures" or "of two natures"; two wills or one will; latreia icons or proskynesis images; the creation or uncreated nature of divine "energies", the procession "from the Son" or "through the Son" – these topics were discussed by Byzantine Christians for many centuries. It may seem that the spirit of Greek Christianity consisted precisely in the optimistic belief that human language is essentially capable of expressing religious truth, and that salvation depends on the accuracy of expression used to convey the meaning of the gospel. However, these same Greek Christians firmly confessed the impossibility of expressing in the language of concepts the fullness of truth and the inability of the human mind to comprehend the essence of God. In Byzantium, therefore, there was an antinomy in the very approach to theology: God did reveal Himself in Christ Jesus, and the knowledge of His Truth is essential for salvation, but at the same time God is above human reason and cannot be fully expressed in human words.

In Byzantium, theology was never the monopoly of professionals or the "teaching church." Throughout the Byzantine period, there was not a single church council whose decisions were not challenged, and the attempts of some emperors to regulate the freedom of conscience of their subjects by means of decrees were met not so much with resistance from a consistently independent hierarchy as with silent resistance to the fullness of the body of the Church. This lack of a clear and legally defined criterion for Orthodoxy implied that the responsibility for interpreting the truth was shared by all. Most of the laity, of course, followed the most prominent bishops, whose teachings were never questioned, or prominent monks, who often played a major role in doctrinal discussions. But ordinary believers also knew how to resolve theological questions, especially when there was no unity of views in the episcopate. Suffice it to recall the testimony of Gregory of Nazianzus, who complained about merchants who argued in the market about the concept of "consubstantial."

The intervention of emperors in theological disputes, which is now perceived as an intolerable encroachment of secular power on the sacred domains of the Church, was considered something common in an era when the law required the emperor to be "glorious in his divine zeal and instructed in the doctrine of the Holy Trinity." Although no one was prepared to grant the emperor the privilege of infallibility, yet no one opposed him to expressing theological views, which de facto acquired greater, and sometimes decisive, weight because they were voiced by the autocrat.

Caesaropapism, however, never became the accepted beginning of Byzantine life. Innumerable ascetics of the faith were constantly extolled precisely for their opposition to the heretical emperors; the hymns sung in the churches glorified Basil for his disobedience to Valens, Maximus for his martyrdom under Constantius, and the innumerable multitudes of monks who resisted the iconoclastic emperors in the eighth century.

Throughout Byzantine history, it was the monks who truly bore witness to the internal independence of the Church. And the fact that the Byzantine Church was primarily the Church of monastics was reflected in the character of Greek theology. It is not surprising, therefore, that those emperors who decided to strengthen iconoclasm had to support the anti-monastic movement in the Church first, since monasticism was necessarily hostile to the Caesaropapist system, to which individual emperors showed a predisposition.

The monks, who numbered in the thousands in Constantinople itself, in all the principal cities, and in practically all parts and corners of the Byzantine world, were firmly opposed to compromise in matters of doctrine; The monks, as a rule, defended the strictest orthodoxy, but it happened that some of them put their zeal in the service of Monophysitism or Origenism. From the sixth century onwards, almost exclusively monastics were elected as candidates for bishops, so that Byzantine spirituality and most of the Byzantine liturgy were formed under the influence of monks. Byzantine Christianity lacked what is today called the "theology of the worldly," and for this the predominant position of monasticism is responsible. However, the same predominance of monasticism did not allow the Christian Church to be fully identified with the empire, and the latter was tirelessly inclined to try to give itself a sacramental character and to adapt the Divine plan of salvation to its transitory needs. It was precisely the quantitative, spiritual and intellectual power of Byzantine monasticism that was the decisive factor in the preservation in the Church of the fundamental eschatological dimension of the Christian faith.

As the last of the main introductory remarks on the specific features of Byzantine theology, attention should be paid to the importance of the Liturgy for Byzantine religious views. In the Eastern Christian world, the Eucharistic Liturgy, more than anything else, was identified with the reality of the Church herself, for the Liturgy revealed both the humiliation of God in His mortal flesh and the mysterious Presence among men of the eschatological Kingdom. The liturgy points to such basic realities of faith not through concepts, but through symbols and signs that are intelligible to the entire assembly of believers. This central position of the Eucharist is the true key to the Byzantine understanding of the Church both as a hierarchy and as a community; The Church is universal, but it is truly realized only in the local assembly of communicants, when sinful men and women truly become "the people of God." This Eucharist-centered view of the Church led the Byzantines to adorn and color the sacrament with elaborate and sometimes burdensome ceremonies and an extremely rich hymnography subordinated to everyday, weekly, Pascha, and annual cycles. These cycles are another true source of theology, along with that sacramental ecclesiology implied by the Eucharist itself. For many centuries the Byzantines not only listened to theological lectures and composed and read theological treatises; they also sang and contemplated the Christian Sacrament daily in the Liturgy, and the richness of expression in the Byzantine Liturgy is incomparable to anything that can be found in the rest of the Christian world. Even after the fall of Byzantium, when Eastern Christians lost schools, books, and all intellectual guidance, it was the Liturgy that remained the main teacher and guide of Orthodoxy. Liturgical texts were translated into various spoken languages of the Byzantine world – Slavonic, Georgian, Arabic and a dozen others – and this was also a powerful expression of unity in faith and sacramental life.