In a recent faith column on the historic Christian doctrine of theosis (found here), it is asserted that the Latter-Day Saint (LDS) doctrine of exaltation is either equivalent to or a restatement of this classical Christian doctrine. Church fathers (patristic) such as Athanasius, Augustine, and even the recent C.S. Lewis are brought to bear in support of this. However, the thinking behind the two streams of thought are vastly different regardless of any similarity in terminology, as the classical Christian thinking demonstrates.
The doctrine of theosis in classical Christianity can only be understood by the traditional teaching of the Trinity, and in the nature of the Godhead. In other words, both Eastern and Western fathers have in mind the idea of the Trinity as defined at Nicaea and Chalcedon, councils and creeds that are rejected by the LDS. One cannot claim patristic support for a doctrine while rejecting the very nature of patristic thinking. By definition, the three persons of the Trinity (one God in substance) are uncreated, immutable (never changed or changing), eternal, self-existent, Holy, and the supreme and ultimate source of all things, including time and space itself (Augustine, On the Trinity). God is not a man (Hosea 11:9), and has always been God. Humans, while created in the image of God, are finite beings created out of nothing (ex nihilo), and are completely dependent on the Trinitarian God for existence (Tertullian, Against Marcion). Put another way, God minus the universe equals God, while the opposite is impossible.
When the church fathers such as Athanasius, Augustine, and others referred to the doctrine of theosis, these concepts of God and human nature were clearly in mind. In order to reconcile humans to God because of sin, the second person of the Trinity (including all the attributes above, always being God before and never ceasing to be God) took on flesh, humbling himself. By doing so, the gulf between humans and God has been “bridged” for those who have faith in Jesus’ life, death, and Resurrection. The incarnation is God becoming flesh, not a man becoming god by exaltation. Theosis states that because of Christ, believing humans now can be united to him, and become “partakers” or “participants” in the divine nature (2 Peter 1:4). Union with the Trinitarian God of the Bible does not mean we become God in essence, but that we achieve status by grace to be called sons of God as co-heirs of Christ.
Through the sanctifying work of the Holy Spirit, we are cleansed and made more and more like Christ, ultimately perfected in the final judgment and bodily Resurrection. This does NOT mean that humans become God (or even like God) in his essential creator capacity or essential attributes, but that we are changed and glorified by our union in Christ. We still retain our distinction as created humans with personalities, and will always remain human in a glorified state, completely dependent on the supreme Trinitarian God of the universe. The human does not become a god unto himself or by nature, but is united to Christ by grace, pardoned for sin (Oden, Classic Christianity). It must also be remembered that classical Christianity looks forward to the Resurrection of the body, where “people will neither marry nor be given in marriage; they will be like the angels in heaven” (Matthew 22:30).
This concept of the believer’s ultimate glorification and union with Christ in classical Christian teaching is a far cry from the LDS concept of exaltation, in which men can become exactly as God is in essence (including the creation of new worlds), because God was also once a mortal man (Gospel Principles, 1992, 305). Such a view is completely foreign to the church fathers, who believed in the classical view of the Trinity as outlined above, a belief still held by orthodox Christians across denominational lines today. Utilizing these church fathers and the Scriptures in support of a doctrine at variance with classical Christianity is to completely decontextualize both, and is an exercise in eisegesis, or “reading into the text” what one wants to find.