From what I’ve been able to read on the Internet, theosis or “union with God” is an important belief in Eastern Orthodoxy. However, the Orthodox definition of theosis differs from the Mormon concept. For the Orthodox, theosis, while difficult to describe or define, is a sort of mystical post-mortal union with the light, aura, or illumination of God without the loss of individual identities. It seems like the Orthodox theosis is more of an event than a process.
In Mormonism, theosis is literally the belief that humans can become gods through the process of eternal progression. Theosis for Mormons is a process more than an event. According to Mormon Apostle James E. Talmage in his book The Articles of Faith (p. 430):
We believe in a God who is Himself progressive, whose majesty is intelligence; whose perfection consists in eternal advancement–a Being who has attained His exalted state by a path which now His children are permitted to follow, who glory it is their heritage to share.”
With the Mormon belief in eternal progression, both God and man are progressing for the eternities. As one Mormon critic described it: we are, “with respect to knowledge and power on a divine escalator.” This belief is consistent with the teachings of Joseph Smith (late in his life), and particularly Brigham Young.
Members of the Eastern Orthodox Church are uncomfortable with the Mormon concept of theosis. Ironically, in an effort to be historically grounded, Mormon scholars use many of the same patristic (early Christian) sources to defend their version of theosis as do the Orthodox. Mormon scholar feel that the doctrine of the divination of man (man may become a literal god) is not the exclusive teaching of the modern-day LDS Church. Rather, it can be found in early Christian history. For example, St. Athanasius stated “The Word was made flesh in order that we might be enabled to be made gods. . .” According to OrthodoxWiki:
Some Mormons suggest that discussions of theosis by early Church Fathers show an early belief in the Mormon concept of deification, although they disagree with much of the other theology of the same Church fathers, most notably the doctrine of the Trinity.
Richard and Joan Ostling, in their book Mormon America, examined the issue and came to the following conclusion:
It seems clear that support for the Mormon doctrines of a corporeal and limited God, eternal progress, and deification cannot be found in Eastern Orthodoxy, the early church fathers, or the twentieth-century writings of C.S. Lewis (p. 313).
Since the Ostlings (non-Mormon journalists) received generally favorable reviews on their book from both Mormons and non-Mormons, they might be considered neutral parties in this discussion.
However, Bishop Hilarion Alfeyev on the website Orthodox Christianity lists five characteristics of the Orthodox belief in theosis:
- Deification of the human nature is possible because of the Incarnation of God
- Human body takes full part in the process of deification and is deified along with the soul.
- The church sacraments, baptism and the eucharist, are among the most important means for deification.
- Deification is anticipated and begun here on earth, but is fully realized in the afterlife.
- Deification is closely connected with a personal mystical experience with the vision of the divine uncreated light.
I don’t think Mormons would disagree with any of these five points. The only difference is in the end result. Mormons appear to have a more expansive view of an individual’s potential in the eternities.
If one assumes that what was given at the time of Christ was essentially what the people at that time were able to culturally grasp, then maybe it doesn’t matter if there are deep historical roots to the Mormon belief in theosis.