The Eastern Orthodox Church has retained theosis as a concept for theological reflection, while the Western churches, seperated by time, language, and philosophy from Greek thinkers of the early church, have dropped it. In fact, theosis simply does not exist for most contemporary Western theologians…The near disappearance in Western Christendom of an idea that was widely accepted for over a thousand years (including by Latin theologians like Augustine), is a serious loss for the Christian thought and hope.  (Stephen Finlan and Vladimir Kharlamov, Theosis/Deification in Christian Theology: Introduction, pg. 8)

St. Justin the Philosopher ca. 103-165

 But far be such a thought concerning the gods from every well-conditioned soul, as to believe that Jupiter himself, the governor and creator of all things, was both a parricide and the son of a parricide, and that being overcome by the love of base and shameful pleasures, he came in to Ganymede and those many women whom he had violated and that his sons did like actions. But, as we said above, wicked devils perpetrated these things. And we have learned that those only are deified who have lived near to God in holiness and virtue; and we believe that those who live wickedly and do not repent are punished in everlasting fire. (First Apology 21)

And when I saw that they were perturbed because I said that we are the sons of God, I anticipated their questioning:

Justin: Listen, sirs, how the Holy Ghost speaks of this people, saying that they are all sons of the Highest; and how this very Christ will be present in their assembly, rendering judgment to all men. The words are spoken by David, and are, according to your version of them, thus: ‘God stands in the congregation of gods; He judges among the gods. How long do you judge unjustly, and accept the persons of the wicked? Judge for the orphan and the poor, and do justice to the humble and needy. Deliver the needy, and save the poor out of the hand of the wicked. They know not, neither have they understood; they walk on in darkness: all the foundations of the earth shall be shaken. I said, You are gods, and are all children of the Most High. But you die like men, and fall like one of the princes. Arise, O God! judge the earth, for You shall inherit all nations.’ But in the version of the Seventy it is written, ‘Behold, you die like men, and fall like one of the princes,’ in order to manifest the disobedience of men—I mean of Adam and Eve—and the fall of one of the princes, i.e., of him who was called the serpent, who fell with a great overthrow, because he deceived Eve. But as my discourse is not intended to touch on this point, but to prove to you that the Holy Ghost reproaches men because they were made like God, free from suffering and death, provided that they kept His commandments, and were deemed deserving of the name of His sons, and yet they, becoming like Adam and Eve, work out death for themselves; let the interpretation of the Psalm be held just as you wish, yet thereby it is demonstrated that all men are deemed worthy of becoming gods, and of having power to become sons of the Highest; and shall be each by himself judged and condemned like Adam and Eve. Now I have proved at length that Christ is called God. (Dialogue with Trypho the Jew 124)

The end contemplated by a philosopher is likeness to God, so far as that is possible. (Fragments of St. Justin the Martyr: from the writings of Antonius Melissa)

Mathetes ca. 130

And if you love Him, you will be an imitator of His kindness. And do not wonder that a man may become an imitator of God. He can, if he is willing. For it is not by ruling over his neighbours, or by seeking to hold the supremacy over those that are weaker, or by being rich, and showing violence towards those that are inferior, that happiness is found; nor can any one by these things become an imitator of God. But these things do not at all constitute His majesty. On the contrary he who takes upon himself the burden of his neighbour; he who, in whatsoever respect he may be superior, is ready to benefit another who is deficient; he who, whatsoever things he has received from God, by distributing these to the needy, becomes a god to those who receive [his benefits]: he is an imitator of God. (To Diognetus, 10)

St. Irenaeus of Lyons died ca. 202

For who else is there who can reign uninterruptedly over the house of Jacob for ever, except Jesus Christ our Lord, the Son of the Most High God, who promised by the law and the prophets that He would make His salvation visible to all flesh; so that He would become the Son of man for this purpose, that man also might become the son of God? (Against Heresies, Book III:2)

For it is thus that you will both controvert them in a legitimate manner, and will be prepared to receive the proofs brought forward against them, casting away their doctrines as filth by means of the celestial faith; but following the only true and steadfast Teacher, the Word of God, our Lord Jesus Christ, who did, through His transcendent love, become what we are, that He might bring us to be even what He is Himself. (Against Heresies Book V, Preface)

Since the Lord thus has redeemed us through His own blood, giving His soul for our souls, and His flesh for our flesh, and has also poured out the Spirit of the Father for the union and communion of God and man, imparting indeed God to men by means of the Spirit, and, on the other hand, attaching man to God by His own incarnation, and bestowing upon us at His coming immortality durably and truly, by means of communion with God—all the doctrines of the heretics fall to ruin. (Against Heresies, Book V.1)

Theophilus of Antioch died ca. 185

And God having placed man in Paradise, as has been said, to till and keep it, commanded him to eat of all the trees,–manifestly of the tree of life also; but only of the tree of knowledge He commanded him not to taste. And God transferred him from the earth, out of which he had been produced, into Paradise, giving him means of advancement, in order that, maturing and becoming perfect, and being even declared a god, he might thus ascend into heaven in possession of immortality. For man had been made a middle nature, neither wholly mortal, nor altogether immortal, but capable of either; so also the place, Paradise, was made in respect of beauty intermediate between earth and heaven. And by the expression, “till it,” no other kind of labour is implied than the observance of God’s command, lest, disobeying, he should destroy himself, as indeed he did destroy himself, by sin. (To Autolycus Book 2.24)

Clement of Alexandria ca. 150-215

But such a good conscience preserves sanctity towards God and justice towards men; keeping the soul pure with grave thoughts, and pure words, and just deeds. By thus receiving the Lord’s power, the soul studies to be God; regarding nothing bad but ignorance, and action contrary to right reason. And giving thanks always for all things to God, by righteous hearing and divine reading, by true investigation, by holy oblation, by blessed prayer; lauding, hymning, blessing, praising, such a soul is never at any time separated from God. Rightly then is it said, And they who trust in Him shall understand the truth, and those faithful in love shall abide by Him. Wisdom 3:9 …To the likeness of God, then, he that is introduced into adoption and the friendship of God, to the just inheritance of the lords and gods is brought; if he be perfected, according to the Gospel, as the Lord Himself taught. (Stromata, Book VI, 14)

Tertullian ca. 160-220

Truth, however, maintains the unity of God in such a way as to insist that whatever belongs to God Himself belongs to Him alone. For so will it belong to Himself if it belong to Him alone; and therefore it will be impossible that another god should be admitted, when it is permitted to no other being to possess anything of God. Well, then, you say, we ourselves at that rate possess nothing of God. But indeed we do, and shall continue to do— only it is from Him that we receive it, and not from ourselves. For we shall be even gods, if we, shall deserve to be among those of whom He declared, I have said, You are gods, and, God stands in the congregation of the gods. But this comes of His own grace, not from any property in us, because it is He alone who can make gods. The property of Matter, however, he makes to be that which it has in common with God. Otherwise, if it received from God the property which belongs to God—I mean its attribute of eternity— one might then even suppose that it both possesses an attribute in common with God, and yet at the same time is not God. (Against Hermogenes V)

St. Hippolytus of Rome ca. 170-236

And in like manner God commanded, that from earth should arise reptiles and beasts, as well males and females of all sorts of animals; for so the nature of the things produced admitted. For as many things as He willed, God made from time to time. These things He created through the Logos, it not being possible for things to be generated otherwise than as they were produced. But when, according as He willed, He also formed (objects), He called them by names, and thus notified His creative effort. And making these, He formed the ruler of all, and fashioned him out of all composite substances. The Creator did not wish to make him a god, and failed in His aim; nor an angel—be not deceived,— but a man. For if He had willed to make you a god, He could have done so. You have the example of the Logos. His will, however, was, that you should be a man, and He has made you a man. But if you are desirous of also becoming a god, obey Him that has created you, and resist not now, in order that, being found faithful in that which is small, you may be enabled to have entrusted to you also that which is great. (Refutation of All Heresies, Book X.29)

You shall escape the boiling flood of hell’s eternal lake of fire and the eye ever fixed in menacing glare of fallen angels chained in Tartarus as punishment for their sins; and you shall escape the worm that ceaselessly coils for food around the body whose scum has bred it. Now such (torments) as these shall you avoid by being instructed in a knowledge of the true God. And you shall possess an immortal body, even one placed beyond the possibility of corruption, just like the soul. And you shall receive the kingdom of heaven, you who, while you sojourned in this life, knew the Celestial King. And you shall be a companion of the Deity, and a co-heir with Christ, no longer enslaved by lusts or passions, and never again wasted by disease. For you have become god: for whatever sufferings you underwent while being a man, these He gave to you, because you were of mortal mould, but whatever it is consistent with God to impart, these God has promised to bestow upon you, because you have been deified, and begotten unto immortality. This constitutes the import of the proverb, Know yourself; i.e., discover God within yourself, for He has formed you after His own image. For with the knowledge of self is conjoined the being an object of God’s knowledge, for you are called by the Deity Himself. Be not therefore inflamed, O you men, with enmity one towards another, nor hesitate to retrace with all speed your steps. For Christ is the God above all, and He has arranged to wash away sin from human beings, rendering regenerate the old man. And God called man His likeness from the beginning, and has evinced in a figure His love towards you. And provided you obey His solemn injunctions, and becomest a faithful follower of Him who is good, you shall resemble Him, inasmuch as you shall have honour conferred upon you by Him. For the Deity, (by condescension,) does not diminish anything of the divinity of His divine perfection; having made you even god unto His glory! (ibid., Book X.30)

St. Cyprian of Carthage died ca. 258

This is our God, this is Christ, who, as the mediator of the two, puts on man that He may lead them to the Father. What man is, Christ was willing to be, that man also may be what Christ is. (Treatise VI, On the Vanity of Idols 11)

And that the proof might not be the less substantial, and the confession of Christ might not be a matter of pleasure, they are tried by tortures, by crucifixions, by many kinds of punishments. Pain, which is the test of truth, is brought to bear, that Christ the Son of God, who is trusted in as given to men for their life, might not only be announced by the heralding of the voice, but by the testimony of suffering. Therefore we accompany Him, we follow Him, we have Him as the Guide of our way, the Source of light, the Author of salvation, promising as well the Father as heaven to those who seek and believe. What Christ is, we Christians shall be, if we imitate Christ. (ibid., 15)

Origen of Alexandria ca. 185-254

 Either they deny that the Son has a distinct nature of His own besides that of the Father, and make Him whom they call the Son to be God all but the name, or they deny the divinity of the Son, giving Him a separate existence of His own, and making His sphere of essence fall outside that of the Father, so that they are separable from each other. To such persons we have to say that God on the one hand is Very God (Autotheos, God of Himself); and so the Saviour says in His prayer to the Father, John 17:3 That they may know You the only true God; but that all beyond the Very God is made God by participation in His divinity, and is not to be called simply God (with the article), but rather God (without article). And thus the first-born of all creation, who is the first to be with God, and to attract to Himself divinity, is a being of more exalted rank than the other gods beside Him, of whom God is the God, as it is written, The God of gods, the Lord, has spoken and called the earth. It was by the offices of the first-born that they became gods, for He drew from God in generous measure that they should be made gods, and He communicated it to them according to His own bounty. The true God, then, is The God, and those who are formed after Him are gods, images, as it were, of Him the prototype. But the archetypal image, again, of all these images is the Word of God, who was in the beginning, and who by being with God is at all times God…Now it is possible that some may dislike what we have said representing the Father as the one true God, but admitting other beings besides the true God, who have become gods by having a share of God. They may fear that the glory of Him who surpasses all creation may be lowered to the level of those other beings called gods. We drew this distinction between Him and them that we showed God the Word to be to all the other gods the minister of their divinity. To this we must add, in order to obviate objections, that the reason which is in every reasonable creature occupied the same relation to the reason who was in the beginning with God, and is God the Word, as God the Word occupies to God. As the Father who is Very God and the True God is to His image and to the images of His image— men are said to be according to the image, not to be images of God— so He, the Word, is to the reason (word) in every man. Each fills the place of a fountain— the Father is the fountain of divinity, the Son of reason. As, then, there are many gods, but to us there is but one God the Father, and many Lords, but to us there is one Lord, Jesus Christ, so there are many Λόγοι, but we, for our part, pray that that one Λόγος may be with us who was in the beginning and was with God, God the Logos. For whoever does not receive this Logos who was in the beginning with God, or attach himself to Him as He appeared in flesh, or take part in some of those who had part in this Logos, or whoever having had part in Him falls away from Him again, he will have his portion in what is called most opposite to reason. (Commentary on the Gospel of John Book II, 2-3)

St. Athanasius of Alexandria ca. 293-373

He became man so that we might be made god; and He manifested Himself in the flesh, so that we might grasp the idea of the uneen Father; and He endured the insolence of men, so that we might receive the inheritence of immortality. (On the Incarnation of the Word, 54:3)

For what the human Body of the Word suffered, this the Word, dwelling in the body, ascribed to Himself, in order that we might be enabled to be partakers of the Godhead of the Word. And verily it is strange that He it was Who suffered and yet suffered not. Suffered, because His own Body suffered, and He was in it, which thus suffered; suffered not, because the Word, being by Nature God, is impassible. And while He, the incorporeal, was in the passible Body, the Body had in it the impassible Word, which was destroying the infirmities inherent in the Body. But this He did, and so it was, in order that Himself taking what was ours and offering it as a sacrifice, He might do away with it, and conversely might invest us with what was His… (Epistle to Epicetus, 6)

St. Hilary of Poitiers ca. 300-368

But the Incarnation is summed up in this, that the whole Son, that is, His manhood as well as His divinity, was permitted by the Father’s gracious favour to continue in the unity of the Father’s nature, and retained not only the powers of the divine nature, but also that nature’s self. For the object to be gained was that man might become god. But the assumed manhood could not in any wise abide in the unity of God, unless, through unity with God, it attained to unity with the nature of God. Then, since God the Word was in the nature of God, the Word made flesh would in its turn also be in the nature of God. Thus, if the flesh were united to the glory of the Word, the man Jesus Christ could abide in the glory of God the Father, and the Word made flesh could be restored to the unity of the Father’s nature, even as regards His manhood, since the assumed flesh had obtained the glory of the Word. Therefore the Father must reinstate the Word in His unity, that the offspring of His nature might again return to be glorified in Himself: for the unity had been infringed by the new dispensation, and could only be restored perfect as before if the Father glorified with Himself the flesh assumed by the Son. (On the Trinity, Book IX.38)

St. Ephrem the Syrian ca. 306-373

…had the serpent been rejected, along with the sin, they would have eaten of the Tree of Life, and the Tree of Knowledge would not have been withheld from them any longer; from the one they would have acquired infallible knowledge, and from the other they would have acquired divinity (allahutha) in humanity; and had they thus acquired infallible knowledge and immortal life, they would have done so in this body. (Commentary on Genesis II.23)

The Most High knew that Adam wanted to become a god, so He sent His Son who put him on in order to grant him his desire. (Nisibene Hymns LXIX. 12)

He gave us divinity, we gave Him humanity. (Hymn on Faith V.17)

Sebastian Brock, Introduction to Hymns on Paradise pg. 73: It has sometimes been said that the concept of the divinization, or theois, of humanity is something that crept into Christianity, and especially under Eastern Christianity, under Hellenic influence. It is clear, however, that St. Ephrem, whom Theodoret described as “unacquainted with the language of the Greeks” (Eccles. History IV.29), and whose thought patterns are essentially Semitic and Biblical in character, is nonetheless an important witness to this teaching. Moreover in this context it should be recalled that, since the term “son of” implies “belonging to the category of,” the title “children of God” to which Christians attain at Baptism would suggest to the Semitic mind that they had, potentially, the characteristics of divine beings, in other words, immortality.

St. Basil of Caesarea ca. 329-379

St. Gregory the Theologian ca. 329-389

Stephen Finlan and Vladimir Kharlamov, Introduction to Theosis/ Deification in Christian Theology, pg. 1:  Deification was an important idea in the early church, though it took a long time for θεωσις (theosis) to emerge as the standard label for the process. The term was coined by the great fourth century theologian, Gregory of Nazianzus.  

 (*) Excerpted from the footnotes Ch. V of Scripture and Tradition (Etna, CA:   Center for Traditionalist Orthodox Studies, 1994 [1984]), 67-75: We cannot overemphasize the deep spiritual reality of the nature of theosis. This is not to belabor the point needlessly. Being alien to a Western theological outlook, the spiritual sense of theosis, as found in the Patristic literature, is often even distorted as witnessed by various indefensibly mistranslated passages from the Greek. An egregious example of this tendency is found in Schaff and Wace’s English presentation of St. Gregory Nazianzus’ first oration, “On Easter and His Reluctance” (Fathers, VII, pp. 203-204). St. Gregory is quoted as exhorting us to “become God’s for His sake, since He for ours became man” [p. 203]. This incredible translation is a rendering of the Greek, “genometha theoi di’ auton, epeide kakeinos di’ emas anthropos” (PG. XXXV, col. 397). We find the following the only suitable translation: “Let us become gods for Him [His sake], since He for us [our sake] became man.” It is simply impossible to find in the words “genometha theoi di’ auton” genitive expression “become God’s [emphasis ours] for His sake.” We can only presume that the theological sensibilities of the translator prevailed over good scholarship, resulting in a fraudulent translation. 

 For He Whom you now treat with contempt was once above you.  He Who is now Man was once the Uncompounded. What He was He continued to be; what He was not He took to Himself.  In the beginning He was, uncaused; for what is the Cause of God?  But afterwards for a cause He was born.  And that came was that you might be saved, who insult Him and despise His Godhead, because of this, that He took upon Him your denser nature, having converse with Flesh by means of Mind.  While His inferior Nature, the Humanity, became God, because it was united to God, and became One Person because the Higher Nature prevailed in order that I too might be made god so far as He is made Man.(Oration 29, 19)

 For there is One God, and One Mediator between God and Man, the Man Christ Jesus. For He still pleads even now as Man for my salvation; for He continues to wear the Body which He assumed, until He make me god by the power of His Incarnation; although He is no longer known after the flesh -I mean, the passions of the flesh, the same, except sin, as ours. (Oration 30, 14)

Blessed Augustine of Hippo ca. 354-430

It is evident, therefore, that He called men gods because they were deified by His grace, and not because they were born of His substance. For He justifies, being just of Himself and not from another; and He deifies, being God of Himself and not by participation in another. But He that justifies does also deify, because by justifying He makes sons of God. For, “He has given them the power to become sons of God.” If we are made sons of God, we are also made gods; but this is by grace adopting, and not by nature begetting. (Enarrationes in Psalmos 49, 2)

Great might is needed to raise up the lowly, to deify a mere mortal, to make the weak perfect, to grant glory through abasement and victory through suffering. (ibid., 117:11)

And there He stood in front of the eyes of a servant, in the form of a servant, saving the form of God for deifed eyes, and He said to him, Am I with you all this time, and you do not know me? (Sermons 126.14)

God, you see, wants to make you a god; not by nature of course, like the One whom He begot; but by His gift and by adoption. (Sermons 166.4)

And being thence warned to return to myself, I entered into my inward self, Thou leading me on; and I was able to do it, for You had become my helper. And I entered, and with the eye of my soul (such as it was) saw above the same eye of my soul, above my mind, the Unchangeable Light. Not this common light, which all flesh may look upon, nor, as it were, a greater one of the same kind, as though the brightness of this should be much more resplendent, and with its greatness fill up all things. Not like this was that light, but different, yea, very different from all these. Nor was it above my mind as oil is above water, nor as heaven above earth; but above it was, because it made me, and I below it, because I was made by it. He who knows the Truth knows that Light; and he that knows it knows eternity. Love knows it. O Eternal Truth, and true Love, and loved Eternity! You are my God; to You do I sigh both night and day. When I first knew You, You lifted me up, that I might see there was that which I might see, and that yet it was not I that did see. And Thou beat back the infirmity of my sight, pouring forth upon me most strongly Your beams of light, and I trembled with love and fear; and I found myself to be far off from You, in the region of dissimilarity, as if I heard this voice of Yours from on high: I am the food of strong men; grow, and you shall feed upon me; nor shall you convert me, like the food of your flesh, into you, but you shall be converted into me. And I learned that You correct man for iniquity, and You make my soul consume away like a spider. And I said, Is Truth, therefore, nothing because it is neither diffused through space, finite, nor infinite? And You cried to me from afar, Yea, verily, ‘I Am that I Am.’ And I heard this, as things are heard in the heart, nor was there room for doubt; and I should more readily doubt that I live than that Truth is not, which is clearly seen, being understood by the things that are made. Romans 1:20 (Confessions Book VII.10)

St. Cyril of Alexandria ca. 376-444

For since they received the Son through faith, they receive the power to be ranked among the sons of God. For the Son gives what is His alone and specially and of nature to be in their power, setting it forth as common, making this a sort of image of the love for man that is inherent to Him, and of His love for the world. For in none other way could we who bore the image of the earthy escape corruption, unless the beauty of the image of the heavenly were impressed upon us, through our being called to sonship. For being partakers of Him through the Spirit, we were sealed unto likeness with Him and mount up to the primal character of the Image after which the Divine Scripture says we were made. For thus hardly recovering the pristine beauty of our nature, and re-formed unto that Divine Nature, shall we be superior to the ills that have befallen us through the transgression. Therefore we mount up unto dignity above our nature for Christ’s sake, and we too shall be sons of God, not like Him in exactitude, but by grace in imitation of Him. For He is Very Son, existing from the Father; we adopted by His Kindness, through |105 grace receiving I have said, Ye are gods and all of you are children of the Most High. For the created and subject nature is called to what is above nature by the mere nod and will of the Father: but the Son and God and Lord will not possess this being God and Son, by the will of God the Father, nor in that He wills it only, but beaming forth of the Very Essence of the Father, He receives to Himself by Nature what is Its own Good. And again He is clearly seen to be Very Son, proved by comparison with ourselves. For since that which is by Nature has another mode of being from that which is by adoption, and that which is in truth from that which is by imitation, and we are called sons of God by adoption and imitation: hence He is Son by Nature and in truth, to Whom we made sons too are compared, gaining the good by grace instead of by natural endowments. (Commentary on the Gospel of John, Bk. I Chap. 9)

St. Patrick of Ireland ca. 387-493

St. Macarius the Great ca. 4th cent.

Abba Alonius ca. 5th cent.

He also said, ‘If only a man desired it for a single day from morning till night, he would be able to come to measure of God.’ (The Sayings of the Desert Fathers: The Alphabetical Collection, Saying 3)

St. Dionysius the Areopagite ca. 5th cent.

The source of this hierarchy is the font of life, the being of goodness, the one cause of everything, namely, the Trinity which in goodness bestow’s being and well-being on everything. Now this blessed Deity, which transcends everything and which is one and also triune has resolved, for reasons unclear to us but obvious to itself, to ensure the salvation of rational beings, both ourselves and those beings who are our superiors. This can only happen with the divinization of the saved. And divinization consists of being as much as possible like and in union with God. (The Ecclesiastical Hierarchy I.3)

The hierarch, “who desires all men to be saved and to come to the knowledge of the truth” (1 Tim. 2:4) by taking on a likeness to God, proclaims the good news to all that God out of his own natural goodness is merciful to the inhabits of earth, that because of His love for humanity He has deigned to come down to us and that, like a fire, He has made one with Himself all those capable of being divinized. “For to all who received Him, who believed in His name, He gave the power to become the children of God; who were born not of blood nor the will of the flesh but of God.” (Jn. 1:12) (ibid., Chap. II.2.1)

St. Benedict of Nursia ca. 480-547

Let us arise, then, at last, for the Scripture stirs us up, saying, “Now is the hour for us to rise from sleep” (Rom. 13:11). Let us open our eyes to the deifying light, let us hear with attentive ears the warning which the divine voice cries daily to us… (The Rule of St. Benedict, Prologue)

St. Barsanuphius ca. 6th cent.

…[B]eing in this state they [the saints] have reached the measure above distraction and high-mindedness — having become wholly mind, wholly eye, wholly light, wholly perfect, wholly gods. Having labored, they became magnified, glorified, enlightened, alive again, because they died to everything. They are now rejoicing and cause joy to all; they are rejoicing over the undivided Trinity, and give joy to the angelic powers. (Answer 120)

St. Maximus the Confessor ca. 580-662

Age, time, and place belong in the category of the relative. Without them nothing of what is included in them exists. God is not of the category of the relative because He does not have anything at all included in Him. If, then, the inheritance of those who are worthy is God Himself, the one who is rendered worthy of this grace will be above age, time, and place. He will have God Himself as a place, according to what is written, “Be for me a protecting God, a strong place which saves me.” (Ps. 71:3) (Chapters on Knowledge, First Century 68)

[W]hen what is partial ceases with the appearance of what is perfect, all mirrors and hidden meanings pass away; once the truth arrives face to face, the one who is saved will be above all worlds, ages, and places in which he was once nurtured as a child, and will reach his end in God. (ibid., First Century 70)

Which exactly the great apostle teaches mystically and says that in the ages to come the superabundant wealth of God’s goodness will be revealed. Therefore, let us too divide the ages in our mind and appoint the one part of them to the mystery of the divine incarnation, and the other part to the grace of the human deification, and we will find the first part to have been completed accordingly, and the other part not yet arrived. And to speak shortly, the first part of the ages belongs to the descent of God to men, and the other part to the ascent of men to God. (To Thalassius, Q.22)

St Symeon the New Theologian ca. 949-1022

And how is it that one made god by grace and by adoption will not be god in awareness and knowledge and contemplation, he who has put on the Son of God? (Introduction to the Discourses, pg. 36)

Display a worthy penitence by means of all sorts of deeds and words, that you may draw yourselves the grace of the all-holy Spirit. For this Spirit, when He descends on you, becomes like a pool of light to you, which encompasses you completely in a inutterable manner. As it regenerates you, it changes you from corruptible to incorruptible, from mortal to immortal, from sons of men into Son of God and gods by adoption and grace… (Discourses, XXXIII)

St. Gregory Palamas ca.  1296-1359

The splendour granted by the grace of God is light, as you may learn from this text: “The splendour for those who who have been purified is light, for the just will shine like the sun; God will stand in the midst of them, distributing and determining the dignities of blessedness, for they are gods and kings.” (The Triads, E. The Uncreated Glory)