Definitions for "Theosis"
(Gr., "deification"): pseudo-Dionysios the Aereopagite defines theosis as "[consisting] of being as much as possible like and in union with God;" a state off being only possible through the agency of the grace of God. Hesychast thinkers saw the divine light that shone at the Transfiguration as the revelation of theosis.
A Greek term used by Christian theologians from the early centuries which denotes the ultimate stage of perfection of human beings. Adam and Eve were created "in the Image of God" with the purpose of becoming perfect and holy "in His likeness." This state of perfection and holiness, a dynamic (not static) condition of human existence, is called theosis.
The concept that Christians can become participants in the life of God, while not sharing in God's essence. The precise definition varies among Christian denominations and theologians. This is based, in part, on 2 Peter 1:4: " Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature..."