In Christian theology, divinization (deification, making divine, or theosis) is the transforming effect of divine grace, the spirit of God, or the atonement of Christ. It literally means to become more divine, or to become god.
There were many varied references to divinization in the writings of the Church Fathers.
In the second century, Irenaeus, bishop of Lyons (c. 130–202) said that God "became what we are in order to make us what he is himself." Irenaeus also wrote, "If the Word became a man, It was so men may become gods." He added:
Do we cast blame on him [God] because we were not made gods from the beginning, but were at first created merely as men, and then later as gods? Although God has adopted this course out of his pure benevolence, that no one may charge him with discrimination or stinginess, 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 be exhibited, then after that what was mortal would be conquered and swallowed up in immortality.
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."