Athanasius of Alexandria wrote, "He was incarnate that we might be made god" (Αὐτὸς γὰρ ἐνηνθρώπησεν, ἵνα ἡμεῖς θεοποιηθῶμεν). His statement is an apt description of the doctrine. What would otherwise seem absurd—that fallen, sinful man may become holy as God is holy—has been made possible through Jesus Christ, who is God incarnate. Naturally, the crucial Christian assertion, that God is One, sets an absolute limit on the meaning of theosis: as it is not possible for any created being to become God ontologically, or even a necessary part of God (of the three existences of God called hypostases), so a created being cannot become Jesus Christ, the Holy Spirit nor the Father of the Trinity.
Most specifically creatures, i.e. created beings, cannot become God in His transcendent essence, or ousia, hyper-being (see apophaticism). Such a concept would be the henosis, or absorption and fusion into God of Greek pagan philosophy. However, every being and reality itself is considered as composed of the immanent energy, or energeia, of God. As energy is the actuality of God, i.e. his immanence, from God's being, it is also the energeia or activity of God. Thus the doctrine avoids pantheism while partially accepting Neoplatonism's terms and general concepts, but not its substance (see Plotinus).
Maximus the Confessor wrote:
A sure warrant for looking forward with hope to deification of human nature is provided by the Incarnation of God, which makes man God to the same degree as God Himself became man ... . Let us become the image of the one whole God, bearing nothing earthly in ourselves, so that we may consort with God and become gods, receiving from God our existence as gods. For it is clear that He Who became man without sin (cf. 4:15) will divinize human nature without changing it into the Divine Nature, and will raise it up for His Own sake to the same degree as He lowered Himself for man's sake. This is what St[.] Paul teaches mystically when he says, 'that in the ages to come he might display the overflowing richness of His grace' (2:7)