In Christian theology, divinization ("divinization" may also refer to apotheosis, lit. "making divine"), or theopoesis or theosis, is the transforming effect of divine grace, the spirit of God, or the atonement of Christ. Although it literally means to become divine, or to become God, most modern Christian denominations do not interpret the doctrine as implying an overcoming of a fundamental ontological difference between God and humanity; for example, John of the Cross (AD 1542–1591) indicated that while "God communicates to it [the individual soul] His supernatural Being, in such wise that it appears to be God Himself, and has all that God Himself has", yet "it is true that its natural being, though thus transformed, is as distinct from the Being of God as it was before". and who was bishop of the church of Lyon in France. For example, in the preface to his apologetic work Adversus Haereses (Against Heresies) vol. 5, Irenaeus states that "[T]he Word of God, our Lord Jesus Christ ... did, through His transcendent love, become what we are, that He might bring us to be even what He is Himself"." Athanasius of Alexandria was an author of the phrase about Jesus Christ which has become popular in Christmas homilies: "He was made human so that he might make us sons of God" (De incarnatione 54,3, cf. Contra Arianos 1.39). Divinization in the context of the Eucharist was taught by Gregory of Nyssa and Cyril of Alexandria. The term never meant for them breaching the absolute ontological distinction between God and his creation.

There were many different references to divinization in the writings of the Church Fathers.

As previously noted, in the second century, Irenaeus, bishop of Lyon (c. 130–202) said that the Word Jesus Christ had "become what we are, that He might bring us to be even what He is Himself."</blockquote>

At about the same time, Clement of Alexandria (c. 150–215), wrote: "Yea, I say, the Word of God became a man so that you might learn from a man how to become a god." Clement further stated that "[i]f one knows himself, he will know God, and knowing God will become like God. . . . His is beauty, true beauty, for it is God, and that man becomes a god, since God wills it. So Heraclitus was right when he said, 'Men are gods, and gods are men.'" Clement of Alexandria also stated that "he who obeys the Lord and follows the prophecy given through him ... becomes a god while still moving about in the flesh."

Justin Martyr (c. 100–165) insisted that in the beginning men "were made like God, free from suffering and death," and that they are thus "deemed worthy of becoming gods and of having power to become sons of the highest."

Athanasius, bishop of Alexandria (c. 296–373), stated his belief in literal deification: "The Word was made flesh in order that we might be made gods. ... Just as the Lord, putting on the body, became a man, so also we men are both deified through his flesh, and henceforth inherit everlasting life." Athanasius also observed: "For the Son of God became man so that we might become God."

Augustine of Hippo (354–430) said: "But he himself that justifies also deifies, for by justifying he makes sons of God. 'For he has given them power to become the sons of God' [referring to John 1:12]. If then we have been made sons of god, we have also been made gods." "To make human beings gods," Augustine said, "He was made man who was God" (sermon 192.1.1). Augustine goes on to write that "[they] are not born of His Substance, that they should be the same as He, but that by favour they should come to Him... (Ibid)".

Other references to divinization in the writings of the Church Fathers include the following:

  • Irenaeus (c. 130-200)
  • "[T]he 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."
  • "'For we cast blame upon [God], because we have not been made gods from the beginning, but at first merely men, then at length gods; although God has adopted this course out of His pure benevolence, that no one may impute to Him invidiousness or grudgingness he declares, "I have said, Ye are gods; and all of you are sons of the Most High." "
  • "For it was necessary, at first, that nature should be exhibited; then, after that, that what was mortal should be conquered and swallowed up by immortality, and the corruptible by incorruptibility, and that man should be made after the image and likeness of God."
  • "For if one knows himself, he will know God; and knowing God, he will be made like God"
  • "[H]is is beauty, the true beauty, for it is God; and that man becomes God, since God so wills. Heraclitus, then, rightly said, "Men are gods, and gods are men." For the Word Himself is the manifest mystery: God in man, and man God"
  • "And to be incorruptible is to participate in divinity..."
  • Justin Martyr (c. 100-165)
  • "[Men] 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."
  • Theophilus of Antioch (c. 120-190)
  • "For if He had made him immortal from the beginning, He would have made him God. Again, if He had made him mortal, God would seem to be the cause of his death. Neither, then, immortal nor yet mortal did He make him, but, as we have said above, capable of both; so that if he should incline to the things of immortality, keeping the commandment of God, he should receive as reward from Him immortality, and should become God..."
  • Hippolytus of Rome (c. 170-235)
  • "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."
  • "If, therefore, man has become immortal, he will also be God. And if he is made God by water and the Holy Spirit after the regeneration of the laver he is found to be also joint-heir with Christ after the resurrection from the dead."
  • Athanasius of Alexandria (c. 296-373)
  • "Therefore He was not man, and then became God, but He was God, and then became man, and that to deify us"
  • "for as the Lord, putting on the body, became man, so we men are deified by the Word as being taken to Him through His flesh."
  • "For He was made man that we might be made God."
  • Gregory of Nyssa (c. 335-395)
  • "Since the God who was manifested infused Himself into perishable humanity for this purpose, viz. that by this communion with Deity mankind might at the same time be deified, for this end it is that, by dispensation of His grace, He disseminated Himself in every believer."
  • "For just as He in Himself assimilated His own human nature to the power of the Godhead, being a part of the common nature, but not being subject to the inclination to sin which is in that nature (for it says: "He did no sin, nor was deceit found in his mouth), so, also, will He lead each person to union with the Godhead if they do nothing unworthy of union with the Divine."
  • Augustine of Hippo (c. 354-430)
  • "'For He hath given them power to become the sons of God.' If we have been made sons of God, we have also been made gods."
  • Maximus the Confessor
  • "Nothing in theosis is the product of human nature, for nature cannot comprehend God. It is only the mercy of God that has the capacity to endow theosis unto the existing... In theosis, man (the image of God) becomes likened to God, he rejoices in all the plenitude that does not belong to him by nature, because the grace of the Spirit triumphs within him, and because God acts in him."
  • Cyril of Alexandria
  • "[H]e came down into our condition solely in order to lead us to his own divine state."
  • "It follows, therefore, that He Who Is, The One Who Exists, is necessarily born of the flesh, taking all that is ours into himself so that all that is born of the flesh, that is us corruptible and perishing human beings, might rest in him. In short, he took what was ours to be his very own so that we might have all that was his."
  • "For we too are sons and gods by grace, and we have surely been brought to this wonderful and supernatural dignity since we have the Only Begotten Word of God dwelling within us."
  • Gregory of Nazianzus
  • implores humankind to "become gods for (God's) sake, since (God) became man for our sake.".
  • Likewise, he argues that the mediator "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."
  • "Through the medium of the mind he had dealings with the flesh, being made that God on earth, which is Man: Man and God blended. They became a single whole, the stronger side predominating, in order that I might be made God to the same extent that he was made man."
  • Basil of Caesarea stated that "becoming a god is the highest goal of all"

Eastern Orthodox

thumb|200px|right|Icon of [[The Ladder of Divine Ascent (the steps toward theosis as described by John Climacus) showing monks ascending (and falling from) the ladder to Jesus, Saint Catherine's Monastery]]

The teaching of deification or theosis in Eastern Orthodoxy refers to the attainment of likeness of God, union with God or reconciliation with God. Deification has three stages in its process of transformation: katharsis, theoria, theosis. Theosis as such is the goal, it is the purpose of life, and it is considered achievable only through a synergy (or cooperation) between humans' activities and God's uncreated energies (or operations). Theosis is an important concept in Eastern Orthodox theology deriving from the fact that Eastern Orthodox theology is of an explicitly mystical character. Theology in the Eastern Orthodox Church is what is derived from saints or mystics of the tradition, and Eastern Orthodoxy considers that "no one who does not follow the path of union with God can be a theologian." In Eastern Orthodoxy, theology is not treated as an academic pursuit, but it is based on revelation (see gnosiology), meaning that Eastern Orthodox theology and its theologians are validated by ascetic pursuits, rather than academic degrees (i.e. scholasticism).

According to the Westminster Dictionary of Christian Theology, as quoted by Millet and Reynolds:

Medieval scholastic theologian Thomas Aquinas wrote:

He also wrote of God's "special love, whereby He draws the rational creature above the condition of its nature to a participation of the Divine good". and he ultimately roots the purpose of the Incarnation in theosis. However, the divinization taught by Aquinas, Augustine, and other Fathers is not ontological, meaning that souls do not take on the substance of God, but rather through grace, are gifted with the participation in the Divine Life.

Of a more modern Roman Catholic theologian it has been said: "The theological vision of Karl Rahner, the German Jesuit whose thought has been so influential in the Roman Catholic Church and beyond over the last fifty years, has at its very core the symbol of theopoiesis. The process of divinization is the center of gravity around which move Rahner's understanding of creation, anthropology, Christology, ecclesiology, liturgy, and eschatology. The importance of this process for Rahner is such that we are justified in describing his overall theological project to be largely a matter of giving a coherent and contemporary account of divinization." Joshua Bloor in his article reveals the rise in deification from an array of Western traditions, looking closely at the Catholic Theologian Catherine LaCugna, arguing that LaCugna sees deification as "personal communion with God, which deifies the human in the process, conforming him/her into being Christ-like".

The Roman Rite liturgy expresses the doctrine of divinization or theosis in the prayer said by the deacon or priest when preparing the Eucharistic chalice: "" ("By the mystery of this water and wine may we come to share in the divinity of Christ who humbled himself to share in our humanity.")

The Catholic Church teaches that God gives to some souls, even in the present life, a very special grace by which they can be mystically united to God even while yet alive: this is true mystical contemplation. This is seen as the culmination of the three states, or stages, of perfection through which the soul passes: the purgative way (that of cleansing or purification, the Greek term for which is , katharsis), the illuminative way (so called because in it the mind becomes more and more enlightened as to spiritual things and the practice of virtue, corresponding to what in Greek is called , theoria), and the unitive way (that of union with God by love and the actual experience and exercise of that love, a union that is called , theosis).

The writings attributed to Dionysius the Areopagite were highly influential in the West, and their theses and arguments were adopted by Peter Lombard, Alexander of Hales, Albert the Great, Thomas Aquinas and Bonaventure. According to these writings, mystical knowledge must be distinguished from the rational knowledge by which we know God, not in his nature, but through the wonderful order of the universe, which is a participation of the divine ideas. Through the more perfect knowledge of God that is mystical knowledge, a knowledge beyond the attainments of reason even enlightened by faith, the soul contemplates directly the mysteries of divine light. In the present life this contemplation is possible only to a few privileged souls, through a very special grace of God: it is the (theosis), (mystical union).

John of the Cross wrote:

Orestes Brownson wrote:

Anabaptist theology

The early Anabaptists wrote quite extensively on the idea of theosis. Hutterite leader Peter Riedemann wrote, for example:

Among the Dutch Mennonites, Dirk Philips and Menno Simons wrote about the concept of theosis in many of their writings. Dirk Philips explained, for example, that although humans cannot become God, per se, they can become like Him in character:

Among the South German Mystics that became Anabaptists, the concept of divinization was also taught. In his confession, Hans Hut explained that holding spiritual communion with Christ would deify a person:

For the early Anabaptist Matthias Servaes, baptism signified a dying to the old nature and "an incorporation into the unity of one mind, resulting in identical natures, patterned after God who is their Father, and becoming dead to the world, that is, to all unrighteousness and crucifying their flesh daily, no longer allowing sin to reign or have the upper hand in them, as Paul clearly tells the Romans (Chapter 6), with many clear words."

Lutheran theology

More recently, the Finnish school of Lutheran thought has drawn close associations between theosis and justification. Primarily spearheaded by Tuomo Mannermaa, this line of theological development grew out of talks between the Evangelical Lutheran Church of Finland and the Russian Orthodox Church between 1970 and 1986. Mannermaa argues in his book, Christ Present in Faith, that the real exchange between Christ and sinful humanity, a theme prevalent in Luther's writing, is synonymous with Eastern views of theosis. It is in this real exchange which Mannermaa says "the union between Christ and the believer makes the latter a ‘completely divine [person] ." While this departure from traditional Lutheran thought is sometimes hailed as "the threshold of a third Luther Renaissance," other Lutheran scholars disagree and argue that the idea of theosis violates Luther's theology of the cross principles by ignoring the real distinction that is axiomatic for not only Luther, but for orthodox Christianity as a whole. One of the most prominent scholars is Robert Kolb, who primarily roots this critique in Luther's use of marriage metaphors concerning the Christian's relationship with God. Kolb writes "This view ignores the nature of the ‘union’ of bride and bridegroom that Luther employed so far."

Reformed theology

Early during the Reformation, thought was given to the doctrine of union with Christ (unio cum Christo) as the precursor to the entire process of salvation and sanctification. This was especially so in the thought of John Calvin.

Henry Scougal's work The Life of God in the Soul of Man is sometimes cited as important in keeping alive among Protestants the ideas central to the doctrine. In the introductory passages of his book, Scougal describes "religion" in terms that evoke the doctrine of theosis:

Anglican theology

Out of the English Reformation, an understanding of salvation in terms closely comparable to the Eastern Orthodox doctrine of theosis was recognized in the Anglican tradition, J. Bloor examines deification/theosis in the late Anglican Priest and theologian Canon A. M. (Donald) Allchin, but it is also explored in the writings of Lancelot Andrewes, who described salvation in terms vividly reminiscent of the early fathers:

C.S. Lewis, speaking on his personal belief in the subject of literal deification, stated as follows:

In a more complete statement on his beliefs in literal deification, C.S. Lewis stated in his book, "Mere Christianity" as follows:

Methodist theology

Theosis as a doctrine developed in a distinctive direction among Methodists, and elsewhere in the pietist movement which reawakened Protestant interest in the asceticism of the early Catholic Church, and some of the mystical traditions of the West. Distinctively, in Methodist (Wesleyan-Arminian) theology, the doctrine of entire sanctification teaches, in summary, that it is the Christian's goal, in principle possible to achieve, to live without any (voluntary) sin (Christian perfection).