"Likeness to God as Far as Possible": Deification Doctrine in Iamblichus and Three Eastern Christian Fathers by Edward Moore, S.T.L., Ph.D. in Theandros: An Online Journal of Orthodox Theology and Philosophy, Volume 3, number 1, Fall 2005.
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From the article:
Deification of the soul is a concept shared by the Hellenic pagan philosophical tradition and Orthodox Christianity. In the ancient Greek language, the concept is denoted by two separate terms. For the pagan Neoplatonists, such as Iamblichus, the deification of the human being was described as henōsis, or unity with God. For Christian theologians of the Greek tradition, the term was theōsis, meaning a divine mode of existence. The difference resides in the ontological and metaphysical presuppositions informing these two philosophical and theological approaches.