Concept

On the Orthodox Faith

Q: Why is it called "Orthodox"?

The Greek title is Ekdosis akribes tes orthodoxou pisteos, "An Exact Exposition of the Orthodox Faith". "Orthodox" here means "right-believing", the faith of the seven Ecumenical Councils (Nicaea I, Constantinople I, Ephesus, Chalcedon, Constantinople II, Constantinople III, and Nicaea II). It is not a denominational label in the modern sense; it is the patristic Christian faith of the first eight centuries.

Q: How did it influence Aquinas?

Substantially. Burgundio of Pisa translated the Exposition into Latin in 1148-1150, and it became one of the major patristic sources for twelfth- and thirteenth-century systematic theology in the West. The Summa Theologiae cites it approximately 1,400 times. Many of the formulations in Aquinas's Christology, Trinity, and angelology come directly from Damascene.

John of Damascus's eighth-century summary of the Christian doctrine inherited from the first seven Ecumenical Councils. The third part of his larger work The Fountain of Wisdom (Pege Gnoseos). One hundred chapters distributed across four books, written in Greek around 743 in the monastery of Mar Saba near Jerusalem. The single most important systematic theology of the Eastern Church and a primary source for Aquinas's Summa Theologiae four centuries later.

Intro

John of Damascus was a Syrian Christian theologian writing under Muslim rule in the eighth century. He had been a high official in the caliph's court in Damascus before retiring to a monastery near Jerusalem. From there he wrote books defending Christian doctrine, including this one, An Exact Exposition of the Orthodox Faith. The book is not original in the way a modern theology book tries to be original. John writes that he is gathering up what the great teachers before him had already said. The result is the most complete summary of Christian doctrine in the Greek tradition for the next thousand years.

The book is in four parts. Part one is on God: the existence and nature of God, the Trinity, the divine attributes. Part two is on creation: angels, demons, the visible world, the human soul and body. Part three is on Christ: the incarnation, the Hypostatic Union, the two wills, the communication of properties, and the theandric activities He performed. Part four is on the Christian life: salvation, the sacraments, Mary, the icons, scripture, the final things.

If you want to know what an educated Christian in the eighth century took the Church's settled doctrine to be, this is the book. It is also why the doctrine of the West and the East has so much in common. Thomas Aquinas had read it, knew it well, and used it constantly when he wrote the Summa Theologiae five hundred years later.

In full

Ekdosis akribes tes orthodoxou pisteos (Greek; Latin De Fide Orthodoxa), c. 743, is the third treatise of John of Damascus's encyclopedic Pege Gnoseos (Fountain of Wisdom / Fountain of Knowledge), the first two being the Dialectica (philosophical preliminaries from Aristotelian logic) and the De Haeresibus (a heresy-catalog). The Exposition is divided into 100 chapters in the standard Greek text, redistributed into four books of 14, 30, 29, and 27 chapters in the Latin tradition that medieval Western theology used. The work is a synthetic compilation: John explicitly disclaims originality, presenting himself as the gatherer of the teaching of "the holy and inspired fathers" (especially Gregory of Nazianzus, Cyril of Alexandria, Maximus the Confessor, and the Corpus Areopagiticum). It was translated into Latin by Burgundio of Pisa in 1148-1150 (De Fide Orthodoxa) and became the standard patristic systematic theology used by Peter Lombard, Bonaventure, and Thomas Aquinas. The Summa Theologiae cites it approximately 1,400 times. The work also exists in Slavonic, Arabic, Armenian, Georgian, and Ethiopic translations, marking it as the most translated patristic systematic theology of the medieval period.

The four-book structure

Book I (chapters 1-14): On God and the Trinity. Opens with the incomprehensibility of God and the limits of theological knowledge. Argues for God's existence, unity, and the Trinity. Treats the divine attributes (simplicity, immutability, eternity, omnipresence, omniscience). Defines the orthodox doctrine of the Trinity from the Cappadocian tradition: one ousia, three hypostaseis. Distinguishes the monarchy of the Father (the Father as principle and source within the Godhead) from any subordination of the Son or Spirit.

Book II (chapters 15-44): On creation, angels, the human person. Cosmology: the visible heavens, the elements, time, space. Angels and demons: their creation, ranks, fall, and current activity. The visible creation: light, fire, air, water, earth. Paradise and the original state. The human person: soul and body, intellect, will, the image of God, free choice, the passions, original sin, the consequences of the fall.

Book III (chapters 45-73): Christology. The incarnation. The two natures of Christ, fully God and fully man. The Hypostatic Union. The Virgin Mary as Theotokos (God-bearer). The two wills (dyothelitism, from the Sixth Ecumenical Council in 681 that John inherits). The two operations (dyoenergism). The communication of properties as the rule for predication. The theandric activities as the rule for how the one Person operates through the two natures. The redemption: Christ's passion, descent into Hades, resurrection, ascension.

Book IV (chapters 74-100): Christian life and the last things. The continuing work of Christ. Baptism, the Eucharist, the cross, the holy icons (chapters 88-90 contain the iconological argument John developed at length in his three Treatises on the Divine Images). The veneration of Mary, the saints, and relics. Scripture. The Antichrist and the resurrection of the dead. The final judgment.

Why the Christology section matters

Book III of the Exposition is the most thorough patristic treatment of two-natures Christology in a single sustained text. John brings together Chalcedonian Christology (Council of Chalcedon, 451), the Cyrilline insistence on the single subject, and the dyothelite and dyoenergist clarifications from the Sixth Ecumenical Council (Constantinople III, 681). The result is the first complete systematic Christology in the wake of the conciliar settlement.

Specific contributions:

The mature articulation of the enhypostatic humanity of Christ: the human nature of Christ has its personal existence (hypostasis) in the Person of the Word, not as a separate human person.
The explicit linking of communicatio idiomatum and theandric activity: predication and operation as two sides of the same Christological doctrine.
The systematic defense of dyothelitism that earlier was scattered across the polemical works of Maximus the Confessor.

Aquinas in the Summa Theologiae III (qq. 1-59) and in the Compendium of Theology (chapters 199-246) draws heavily on this section. So does Réginald Garrigou-Lagrange in Christ the Savior.

Why this matters for apologetics

Three reasons the Exposition is worth reading today.

It is the eighth-century shared inheritance. Before the East-West schism (1054) and before the Reformation (1517), this was the systematic theology of the Christian Church. Catholics, Eastern Orthodox, Oriental Orthodox, and most Protestants can recognize the substance as common Christian doctrine prior to the divisions.
It is one of the primary sources for Aquinas. A working understanding of Damascene is a working understanding of half the citations in the Summa. For anyone reading Aquinas, knowing the source matters.
It is the East's Summa. For understanding Eastern Orthodox theology, no later book is as foundational. The Eastern liturgical tradition, the iconographic theology, the dyothelite Christology, the divine attributes tradition, all live downstream of this book.

Editions

Greek: PG 94, 789-1228 (Patrologia Graeca, ed. J.-P. Migne, 1864). The standard older edition.
Greek (critical): Bonifatius Kotter, Die Schriften des Johannes von Damaskos, vol. II: Expositio Fidei (de Gruyter, 1973). The modern critical text.
English: S. D. F. Salmond, in Nicene and Post-Nicene Fathers, second series, vol. 9 (1899). The standard English public-domain version, also available freely online.
English: Frederic H. Chase, Jr., Saint John of Damascus: Writings (Fathers of the Church, vol. 37, 1958). The standard modern English translation.

Common questions this page answers

Q: What is On the Orthodox Faith?

A summary of Christian doctrine written by John of Damascus around 743, in four books and 100 chapters. It covers the doctrine of God and the Trinity (Book I), creation and the human person (Book II), Christology and the work of Christ (Book III), and the Christian life and the last things (Book IV). It is the most important systematic theology of the Eastern Christian tradition.

Q: Who was John of Damascus?

A Syrian Christian theologian, born around 675 in Damascus, who served in the caliph's court before retiring to the monastery of Mar Saba near Jerusalem. He wrote the Fountain of Wisdom (of which the Exposition is the third part), the three Treatises on the Divine Images defending the use of icons against the iconoclast emperors, and numerous hymns still used in Eastern liturgy. He died around 749 and is venerated as a saint and doctor of the Church in Catholic, Eastern Orthodox, and other traditions.

Q: Why is it called "Orthodox"?

The Greek title is Ekdosis akribes tes orthodoxou pisteos, "An Exact Exposition of the Orthodox Faith". "Orthodox" here means "right-believing", the faith of the seven Ecumenical Councils (Nicaea I, Constantinople I, Ephesus, Chalcedon, Constantinople II, Constantinople III, and Nicaea II). It is not a denominational label in the modern sense; it is the patristic Christian faith of the first eight centuries.

Q: How did it influence Aquinas?

Substantially. Burgundio of Pisa translated the Exposition into Latin in 1148-1150, and it became one of the major patristic sources for twelfth- and thirteenth-century systematic theology in the West. The Summa Theologiae cites it approximately 1,400 times. Many of the formulations in Aquinas's Christology, Trinity, and angelology come directly from Damascene.

Q: What is special about Book III on Christology?

It is the first complete systematic Christology written after the Sixth Ecumenical Council (681), which definitively defined the two-wills doctrine. Book III brings together Chalcedonian two-natures Christology, the Cyrilline doctrine of one subject, the communication of properties, and the theandric activity of Christ in a single sustained text. Every later orthodox Christology is in conversation with Book III.