The statement by St. Athanasius of Alexandria, "The Son of God became man, that we might become god", [the second g is always lowercase since man can never become a God] indicates the concept beautifully. II Peter 1:4 says that we have become " . . . partakers of divine nature." Athanasius amplifies the meaning of this verse when he says theosis is "becoming by grace what God is by nature" (De Incarnatione, I). 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 - it is not possible for any created being to become, ontologically, God or even another god.
Through theoria, the knowledge of God in Jesus Christ, human beings come to know and experience what it means to be fully human (the created image of God); through their communion with Jesus Christ God shares Himself with the human race, in order to conform them to all that God is in knowledge, righteousness and holiness. Theosis also asserts the complete restoration of all people (and of the entire creation), in principle. This is built upon the understanding of the atonement put forward by Irenaeus of Lyons, called "recapitulation."