What Theosis Is Not
WHEN FOSTER PARENTS ADOPT CHILDREN, they are not able to grant to the adopted child their nature, their blood and genes. But in divine adoption, which is a prolongation of the Incarnation, we become partakers of divine nature. Yet, how can man partake of God's nature?
The Church Fathers distinguish between the nature or essence of God and His energies. The nature of God is both participable and unparticipable. It is participable in the uncreated energies but not in its essence. Thus, theosis is not participation in the divine essence. For if we could unite with God's essence, as Vladimir Lossky states, we would cease to be creatures and God would be not a Trinity of Persons, but would have as many hypostases as there are persons participating in His essence. Thus, unity with God in theosis is not pantheism, which believes that everything is God.
St. Gregory Palamas delineates as follows between the essence of God and His energies: "God in His completeness deifies those who are worthy of this, by uniting Himself with them, not hypostatically - that belonged to Christ alone - not essentially, but through a small part of the uncreated energies ... while yet being entirely present in each."
Commenting on II Peter 1:4, St. Nicodemus the Hagiorite wrote:
"But whoever hears (Peter) saying that it has been granted to Christians to be communicants of Divine Nature, let him not be deceived and think he is saying that anyone can partake of the Nature and Essence of God - perish the thought! For this is impossible for a rational creature.... Because ... the infinite Essence and Nature of God is not only unparticipable by creatures, but is also invisible to them, and not only invisible, but also incomprehensible, and in all respects inscrutable and unfathomable. Therefore the communion of the divine of which the ... Apostle here speaks is, namely, that those Christians who have been purified ... will communicate and partake of God's ... energies and powers and graces."
What do we mean when we speak of God's "energies?" Here are some answers.
Divine energies are God Himself as He has manifested Himself to us. They are the ways by which God has come down to us and revealed Himself. Through His energies, God continues to enter into relationship with people. By grace, that is by God's energies, we are no longer separated from God. His energies are the power of His grace, which is experienced by believers today and is called theosis. The vision of the uncreated light experienced by the Hesychasts is a form of God's energies, just as was the light which shown through Christ at the Transfiguration. Grace is understood by the Orthodox as the energies of God in action, making God known and present to us. And grace continuously granted and accepted, results in theosis.
The Christian virtues are ultimately divine energies in which human beings are called to participate. Patience, for example, is a divine energy in which we are called to share through the Holy Spirit. So are love, joy, peace, gentleness, kindness and self-control. These virtues do not emanate from us, but are fruits of energies of the Holy Spirit in us. They are the evidence of the reality of our participation in theosis now. The Church Fathers stress that to exercise any one virtue perfectly, be it forgiveness, or patience of self-control, requires all the virtues.
God is by nature unknowable in His essence. He becomes knowable through His energies, which are the ways by which He, in His grace, has opened Himself to us. "No one has seen God at any time. The only begotten Son, who is in the bosom of the Father, He has declared Him" (John 1:18). Although not capable of knowing God in His essence, we are capable of knowing Him through His energies, since He is present in each of His energies.
When we speak of theosis, then, we mean a union with the energies of God and not with the essence of God, which always remains hidden and unknown. Yet this is a true union with God in which God and man retain their unique characteristics.
St. Basil has written, "We know our God from His energies, but we do not claim that we can draw near to His essence, for His energies come down to us, but His essence remains unapproachable."
Man's knowledge of God can be only of His energies, not of His essence. All of us participate in God's energies, but each one of us differently. Deified humanity is united to God only in grace and energy. George Mantzaridis writes, "Man's deification is not realized through participation in God's essence, but through communion in His divine energy. Man may share in God's glory and brightness, but the divine essence remains inaccessible and nonparticipable. Thus, the deified man is made god in all things, but he neither is identified with the divine essence nor shares it."
Jack Breck summarizes the distinction between the essence and the energies of God as follows:
"...Taking up the distinction between essence and energies that goes back at least to St. Gregory of Nyssa, the Greek patristic tradition affirms that deification is achieved by grace, through the sanctifying power of the divine energies. Humans are not, nor can we ever be 'participants of the divine nature,' if by nature we understand not 'being' (as II Peter 1:4), but the divine essence. For the latter is transcendent and inaccessible to any form of created reality. 'Deification,' therefore, does not suggest that we become God, despite the rather audacious language used by some of the early patristic writers. It means that by the initiative that belongs wholly to the three Divine Persons, humans as creatures are introduced into personal relationships of participation in the uncreated, divine energies or grace. Thereby people become 'by grace' what God is 'by nature.'"
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 Basil. Letter 234, 1. Page 32, 869.
 "The Deification of Man," George Mantzaridis. St. Vladimir Press, Crestwood, NY. 1984. Page 122.
 "Salvation in Christ: An Orthodox-Lutheran Dialogue," Meyendorff and Tobias. Augsburg Publishing House. Minneapolis, Minnesota. 1992.