There are doubtless many differences to be found between groups of Christians - though there is probably more that all Christians share than not. Orthodox Christianity generally holds to those doctrines that were at one time universal and continues to be a watershed of classical Christian faith. It is interesting that some things that many think of as distinctives of Orthodox Christianity have a wider attestation than most people know. These common essentials are often blurred by an emphasis on distinctives or the fact that certain things which have remained central within Orthodoxy have become marginalized in other places.

Perhaps no single doctrine is more classically expressive of the Orthodox faith than the doctrine of the Divine exchange (divinization or theosis). First offered in its most classical form by St. Irenaeus in the 2nd century (though there is ample Scriptural support for the doctrine), it is generally stated: God became man so that man could become god. This same statement of faith, in varying forms can be found in fathers, both East and West.

Daniel Keating has produced a small book on the topic: Deification and Grace. He says:

Following Irenaeus - and probably dependent upon him - we find wide attestation to this formula throughout the patristic period. It is noteworthy that some form of this expression can be found in writers from Alexandria, Constantinople, Antioch, Syria, North Africa, and Rome….

St. Clement of Alexandria:

the Word of God became man, that you may learn from man how man may become God.

St. Athanasius of Alexandria:

For he was made man that we might be made God…and…he himself has made us sons of the Father, and deified men by becoming himself man.

St. Gregory the Theologian:

Let us become as Christ is, since Christ became as we are; let us become gods for his sake, since he became man for our sake.

St. Gregory of Nyssa:

…the Word became incarnate so that by becoming as we are, he might make us as he is.

St. John Chrysostom:

he became Son of man, who was God’s own Son, in order that he might make the sons of men to be children of God.

St. Ephrem the Syrian:

He gave us divinity, we gave him humanity.

St. Hilary of Poitiers (in the West):

For when God was born to be man the purpose was not that the Godhead should be lost, but that, the Godhead remaining, man should be born to be god.

St. Ambrose of Milan:

For [the Son] took on him that which he was not that he might hide that which he was; he hid that which he was that he might be tempted in it, and that which he was not might be redeemed, in order that he might call us by means of that which he was not to that which he was.

St. Augustine of Hippo:

God wanted to be the Son of Man and he wanted men to be the Sons of God.

Pope St. Leo the Great (5th century):

[The Savior] was made the son of man, so that we could be the sons of God…and…He united humanity to himself in such a way that he remained God, unchangeable. He imparted divinity to human beings in such a way that he did not destroy, but enriched them, by glorification.

Even in Protestant writers…

Martin Luther in a Christmas sermon:

For the Word becomes flesh precisely so that the flesh may become word. In other words: God becomes man so that man may become God.

John Calvin, rather eloquently:

This is the wonderful exchange which, out of his measureless benevolence, he has made with us; that, by his descent to earth, he has prepared an ascent to heaven for us; that, by taking on our mortality, he has conferred his immortality upon us; that, accepting our weakness, he has strengthened us by his power; that, receiving our poverty unto himself, he has transferred his wealth to us; that, taking the weight of our iniquity upon himself (which oppressed us), he has clothed us with his righteousness.

This is a wonderful testimony, of almost universal appeal, to one of the central tenets of the Christian faith. Often obscured by other doctrinal formula, it remains central in the Christian East, where the principle of exchange - that God took upon Himself our human condition that we might share in His divinity - runs throughout the whole of doctrine.

Keating’s book is a refreshing read. It was a Christmas present to me from Fr. Alvin Kimel (aka the Pontificator). My deepest thanks.