Vladimir Lossky argues that the way to deification, the original plan for man, is impossible until human nature triumphs over sin and death. For fallen humanity, the way of union is the way of salvation (from death and from sin, its root). There is a triple barrier that separates us from God – death, sin and nature.
This barrier can only be broken through by God in the inverse order, beginning with the union of the separated natures in his Incarnation, through the destruction of sin by his death, and ending with the victory over death by his Resurrection.
The union of the two natures has been determined in the eternal counsel of God, and so deification is the final end for which the world has been created out of nothing. The incarnation is not a matter of necessity, but of the free will of God, a mystery of divine love in which the divine will works in relation to the human will, condescending to human freedom and coordinating in His providence His actions with the acts of created beings, thereby governing the universe without doing violence to human freedom.
In the person of the Virgin, humanity has given its consent to the Word become flesh, and thus in the one and the same act the Word assumed human nature, gave its existence, and deified it. The humanity received its being from the Divine hypostasis, and it was subjected voluntarily to the condition of our fallen nature, in the sense of assuming the consequences of sin, without sinning.
Finite and infinite are united in Him; the hypostasis of the Logos remains God while it becomes flesh – the deity does not become humanity, nor is humanity transformed into deity, but both are united in one hypostasis. He is perfect in deity and in humanity, consubstantial with God and with us respectively in the two natures which are unmixed, unchanged, indivisible, inseparable – the properties of each nature remaining while united in one Person or hypostasis.
In the Person of the Son the common will of the Trinity is done. The kenotic will of the Son penetrates the flesh and gives to in an ineffable faculty of penetrating the Divinity. The body is united to God, and the humanity of Christ is a deified nature that is permeated by the divine energies from the moment of the Incarnation – like iron penetrated by fire, becoming fire, though remaining iron by nature.
Each nature acts according to its own properties (“it is not the human nature that raises Lazarus, nor the divine power that shed tears before his tomb,” says St John of Damascus). He who wills is One, in whom the two wills – divine and human – are united. Christ does not have a gnomic will, which deliberates between choices, as we do, because he has no need of it; but the humanity of Christ always wills divinely, in accordance with the divine will. His body experienced hunger and thirst, his soul grieved, his spirit prayed, and the two natural wills never entered into conflict.
In the Garden of Gethsemane, the human will reacted against death, unnatural to it, but as the divine will wished, the human will voluntarily conformed to the divine will and accepted the Passion. The human will continually renounced what naturally belonged to it, and, in a continual humiliation, accepted what is contrary to incorrupt and deified humanity.
The Transfiguration shows the humanity of the Word deified by the divine energies, revealing the divinity in the splendor of the Three Persons. In his Passion, “He who covers himself with light as with a garment, stood naked before the judges . . . He who suspended the earth upon the waters, is hung on the tree.” Man must be sanctified by the humanity of God, and God himself must deliver us by overcoming the tyrant through his own power. Christ bridges the gulf between God and man by leading him into the heart of his Person, healing all that belongs to man, particularly the will which was the source of his sin.
Thus the whole of our fallen nature (death included) have been transformed by the life-giving Cross, and the three stages of salvation – being (Incarnation), well-being (incorruptibility of the will) and eternal being (Resurrection) are fulfilled. Our salvation is then accomplished by the union of the two natures in the One Person, the natures remaining united while intact, as the divine and human wills and operations remain intact and in full harmony.
What is not assumed cannot be deified, and it is the One Divine Person of the Logos who assumes the full human nature to unite it to the divine nature as they remain unmixed, unchanged, indivisible, inseparable. What is deified in Christ is his human nature assumed in its fullness. A new nature, a restored Creature, appears in the world. A new body, free from sin and necessity, is made, and the way is open for us, as persons, to be united to God by the Holy Spirit as we are united in our natures to God in Christ. The work of Christ is consummated in the work of the Holy Spirit.
-Vladimir Lossky, The Mystical Theology of the Eastern Church, chapter 3 (“The Economy of the Son”).