Christ has shared in our poverty so that we may share in the richness of his divinity: for our sakes He became poor, so that through His poverty we might become rich (2 Cor. 8:9); Christ prayed that we might share in the perichoresis of the Trinity, “that they may be one, just as We are one – I in them, and You in Me, that they may be perfectly one” (John 17:22-23); we have been made “partakers of his divine nature (2 Peter 1:4).
If humans are to share in God’s glory, they are to become by grace what God is by nature, i.e., we are to be deified. As St Athanasius put it,
The Word was made man in order that we might be made divine [also translated, that we might become god]. He displayed himself through a body, that we might receive knowledge of the invisible Father. He endured insult at the hands of men, that we might inherit immortality. 
This is only possible because we are mystically and ontologically united to Christ through faith, in the Holy Spirit; therefore, our redemption and deification is only possible if Christ is fully God and fully human, and if the Holy Spirit himself is also fully God. In fact, this became central in the Father’s arguments for the deity of Christ and of the Holy Spirit in the fourth century. No one less than God can save humanity, and so Christ must be fully God; but only if He is truly human, as we are, can we humans participate in what He has done for us.
Scripture states that human beings have been created in the image and likeness of God (Gen. 1:26). Most of the Greek Fathers made a distinction between those two terms, arguing that the image of God refers to our intellectual capacities and our freedom of will, while the likeness of God refers to our conformity to God according to virtue. Our image has not been lost in the Fall for we retain our reason and human free will; but what Adam failed to do, and that which we must attain through the grace of God enabling our efforts – the synergia of God and man – is likeness to God. To become like God is to acquire divine likeness, to be assimilated to God through virtue, and therefore, to be deified, to become a second god, a god by grace.
Adam and Eve were created in the image and likeness of God, but they still had to mature and progress to a greater likeness. Thus, human beings before the Fall were perfect not so much in an actual but in a potential sense, for, having the image, they were called to acquire the likeness by their own efforts, assisted by the grace of God (cooperation, synergia). As St Irenaeus put it, Adam was in a state of innocence and simplicity, in need of growth unto perfection.
Sin, Grace, Free Will
After the Fall the likeness is not something with which we are endowed from our first moment of existence; it is a goal for which we must aim, something we can only acquire by degrees. However sinful we may be, we never lose the image, but the likeness depends upon our moral choices, upon our virtue, our cooperation with the grace of God – and conversely, this likeness is destroyed by sin.
The Orthodox Church rejects any account of grace that might seem to infringe upon human freedom; therefore, we, as “fellow workers with God” (1 Cor. 3:9) must make our contribution to this common work – although always recognizing that what God does is of immeasurably greater importance than what we do. There are two unequal but necessary forces that cooperate: divine grace and human will.
The paradigm and supreme example of this is seen in the Theotokos, who said “may it be done according to thy will.” We cannot merit salvation, but we must work it out in fear and trembling (Phil. 2:12-13), for faith without works is dead (Jas. 2:17). Sin has restricted the scope of our free will but has not destroyed it.
Acquire the Holy Spirit!
St Seraphim of Sarov taught that “the true aim of the Christian life is the acquisition of the Holy Spirit.” Vladimir Lossky argues that this “sums up the whole spiritual tradition of the Orthodox Church.” The acquisition of the Holy Spirit is nothing other than deification. The final goal at which every Christian must aim is to become god, to attain theosis; for Orthodoxy, our salvation and redemption mean our deification.
Just as the Persons of the Trinity inhere in one another in the divine perichoresis, we also are called to dwell in the Trinitarian God, to share in the life of the Trinity, and to dwell in one another in an unceasing movement of love. This idea of personal and organic union between God and humans – God dwelling in us and we in Him – is often highlighted in the gospel of St John and the epistles of St. Paul; again, St Peter speaks of our sharing in the divine nature.
His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence, by which he has granted to us his precious and very great promises, so that through them you may become partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire. (2 Peter 1:3-4)
A Fourth Member of the Trinity? Essence and Energies.
It is important to note that the idea of deification must always be understood in the light of the distinction between God’s essence and His energies, as St Gregory of Palamas stated, viz., union with God means union with the divine energies, not the divine essence. The latter remains transcendent, inaccessible to creation ontologically, as well as intellectually – thus the need of apophatic theology.
Union with God’s essence would constitute pantheism (or panentheism) which the Orthodox Church rejects. In the mystical union of God and man through deification, the Creator and the creature are not fused into a single being, but remain distinct. Human beings fully retain their personhood even after attaining deification, and their union with God is the analog of the Trinity, where there is unity in diversity. Of course, the distinction being that in the Trinity the Persons share the same numerical nature, whereas human persons only share their specific nature with other humans, and remain human even while participating in the divine nature.
We remain creatures while becoming god by grace, as Christ remained God when becoming man by the Incarnation. We do not become God by nature, but created gods, gods by grace or by status. Nonetheless, deified saints, according to St Maximus, are those who are worthy of God and have one and the same energy with him. Saints do not lose their free will, but when deified they voluntarily conform their will to the will of God in love.
Body and Soul, Heaven and Earth
Deification involves not only the inward person but also the body, for human beings are hylomorphic beings, unities of body and soul, and Christ took upon himself full humanity in order to redeem the whole person. Therefore, according to St Maximus, “our body is deified at the same time as our soul.” Our bodies are the temple of the Holy Spirit, and we are to offer them as living sacrifices to God (1 Cor. 6:19, Rom. 12:1).
The full deification of the body must wait until the Last Day, when our redemption will be fully consummated and the righteous will rise from the dead and be clothed with a spiritual, incorruptible body. In that Day, the glory of the Holy Spirit which now shines hidden in the inward man will transfigure our bodies, coming out from within and shining visibly with the light of Mount Tabor. In the meantime, we receive the firstfruits of our redemption, and as such some saints have experienced tokens of the visible, bodily glorification.
Reports of saints shining visibly in times of prayer include that of St Seraphim of Sarov, Arsenius the Great, Abba Pambo and others. Here in San Francisco, the incorrupt relics of my patron saint, St. John Maximovitch, lie displayed for all to see and venerate at the Holy Virgin Cathedral.
Because the Orthodox are convinced that the body is sanctified and transfigured together with the soul, reverence for the relics of the saints is a natural outcome. The grace of God that is present in the saints’ bodies during their lives remains active when they die, and God uses such bodies as channels of divine power and as instruments of healing. In some cases, the bodies of the saints have been miraculously preserved from corruption; but the reverence and veneration of the relics of the saints is present even when this has not occurred.
Indeed, the doctrine of theosis, which informs a worldview of God suffusing human beings with his grace, in his energies, is also the framework for the understanding that God redeems not only human beings, but all of physical creation as well. Not only our human body but the whole of the material world will be eventually transfigured, for Christ came to make all things new, and God’s redemptive plan culminates in the establishment not only of a new heaven, but also a new earth. Creation is to be saved and glorified along with humans, and icons are the firstfruits of this redemption of matter.
The Incarnation, of course, is both the basis and means through which God redeems all of creation, including matter. Christ took flesh and thus the material order in him was united to God. From his Incarnation springs God’s cosmic redemption, and the Orthodox doctrine of the deification of the body, its iconology, and indeed its view of the holiness and even sacramentality of the created order are firmly grounded on it.
In the Orthodox tradition there is therefore a profound sense of the intrinsic sacredness of the earth, a serious affirmation of the goodness of life and an increasing concern for man’s responsibility as the steward of the planet. According to Ecumenical Patriarch Dimitrios’ 1988 Christmas message, the world “should become a Eucharistic offering to the Creator, a life giving bread, partaken in justice and love with others.”
Six Points to Remember
Metropolitan Kallistos lists six points that must be made in order to avoid misunderstandings concerning the doctrine of theosis:
- First, it must be clear that theosis is for every Christian without exception. The process of divinization begins in this life for all Christians, and not for a select few. However weak our attempts may be to follow Christ and keep his commandments, of using our will in making choices that conform to the grace of God, we are already in some degree deified.
- Secondly, the process of deification does not mean that one becomes perfect or sinless in this life, or that one ceases to be conscious of sin. It was St Paul who called himself the “chief of sinners,” for it is characteristic of great saints to have an acute awareness of their own limitations. Deification always presupposes a continual act of repentance, and it is not for nothing that the Jesus Prayer begs, “Lord Jesus Christ, Son of God, have mercy on me a sinner.” The doctrine of theosis is not mutually exclusive with a doctrine of ongoing penitence, but rather presupposes it.
- Thirdly, theosis does not come about through some esoteric or magical technique. Rather, the process of deification, in which we cooperate with the grace of God, takes place in one’s life through the means God has appointed to bring that about.
- Metropolitan Kallistos lists six such means:
- Church (i.e., participating in the liturgy and in the life of the community),
- The regular reception of the sacraments
- Perseverance in prayer
- The reading of the Gospels
- The keeping of God’s commandments
- Christian service.
- Metropolitan Kallistos lists six such means:
- Therefore, fourthly, deification is not a solitary but a “social” process. The commandments are summed up in the love of God and the love of neighbor. These two are inseparable, for one cannot fulfill one without fulfilling the other. Only if one loves God – and therefore only if one loves his neighbor – can one be deified. As the Persons of the Trinity dwell in one another, so we must also dwell in our neighbors.
- Fifthly, and consequently, theosis is practical because love of God and of our neighbors must be practical, i.e., expressed in action. Obviously the process of theosis does not exclude mystical experience, but it certainly includes the service of love. In our efforts, our synergia, we cooperate with the grace of God by conforming not only our minds and hearts to him, but also in imitating his love through actions.
- Lastly, deification presupposes life in the Church, life in the sacraments, for they are the means appointed by God for us to acquire the Holy Spirit and be transformed in the divine likeness.
 On the Incarnation, 54
 Cf. e.g., St Gregory of Nazianzus’ orations on the Son and on the Holy Spirit against Arianism. Also, as theosis requires not only the full divinity of Christ, but also his full humanity (since he does not redeem what he does not assume), it became important for the Christological discussions concerning the human nature of Christ as well, over against Docetism, Monophysitism, Monothelitism, etc.
 “I said, “You are gods, sons of the Most High, all of you” (Ps. 82:6). “Jesus answered them, Is it not written in your Law, ‘I said, you are gods’?’” (John 10:34).
 Demonstration of the Apostolic Preaching, 12.
 Metropolitan Kallistos points out that this is a different approach than that of Augustine, who viewed humans in Paradise in a state of realized perfection. It is interesting to note that the “magisterial” Reformers (Calvin, Turretin, et. al.) in Protestantism viewed Adam and Eve as being not in a perfect state, but in a state of probation, after the successful completion of which they were to attain glorification through obedience to the “covenant of works.” In that view, Christ came to fulfill that covenant of works as the second Adam, and thereby to impute his perfect obedience and righteousness to those united to him through faith. The idea of imputation (in the forensic, Reformed sense) was foreign to the Fathers (and arguably to the New Testament), but it is interesting to note some similar views the Reformers had with the Greek Fathers concerning Adam’s need to attain likeness to God, in contradistinction to Augustine and later Latin theologians.
 The Mystical Theology of the Eastern Church, p. 196.
 E.g., John 15:1-5 reads, “I am the true vine, and my Father is the vinedresser . . . Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing.”
 E.g., we are members of His body, of His flesh and of His bones (Eph. 5:30), we are members of Christ (1 Cor. 6:15); Christ lives in us (Gal. 2:20) and dwells in our hearts by faith (Eph. 3:17); He is in us (Rom. 8:10), and is to be formed in us (Gal. 4:19); etc.
 There are similar reports of such events in the Western tradition, the example of Anselm of Canterbury perhaps being the most famous.
 As C. S. Lewis has famously stated in Mere Christianity, “God likes matter, He invented it.” Indeed, he also has redeemed it.