This paper aims to explore some of the basic tenets of the Eastern idea of theosis and to try an assessment. The Orthodox theologians hold that theosis has a strong biblical basis. The Petrine passage about our becoming “participants in the divine nature” is understood as meaning that although Christ alone is God by nature, all people are called to become God “by participation.” In the Orthodox theological tradition, the doctrinal basis of man’s deification is found in the hypostatic unity between the divine and the human nature in Christ. Though fully man, Christ does not possess a human hypostasis, which implies that Jesus’ hypostasis has a fundamental affinity with all human personalities. Human persons are called to participate in the deified humanity of Christ’s and to share in its deification. The Orthodox distinction between the divine essence and the divine energies enable the Eastern Church to affirm the possibility of a direct or mystical union between man and God, but at the same time we exclude any pantheistic identification between the two. Also the Orthodox theologians emphasize that a person becomes the perfect image of God by discovering his or her likeness to God, which is the perfection of the nature common to all human beings. While the Western doctrines of sin and salvation have been dominated by legal, juridical and forensic categories, the Byzantine doctrine of theosis clearly shows that salvation is transformation, not simply remissions of sins. Salvation means our being united with God. To be saved is to be one with the Father through the Son in the power of the Holy Spirit. The Orthodox doctrine of theosis has a strong point that it is a more positive concept than ‘remissions of sins,’ or ‘satisfaction,’ which, I believe, may have a corrective value in regard to the ‘forensic’ characteristics of Western soteriologies.