Why aren't others teaching deification (theosis)?
…the concept of deification has been a popular one from the beginning of the Christian church. And modern writers are in fact beginning to ask why their church is not teaching it as doctrine. Lutheran scholar Robert Jenson, in an article in a Lutheran journal on the very topic of theosis, concludes by asking: “Perhaps the question has at least become a bit more urgent: The patristic church proclaimed deification; why do not we?” (Robert W. Jenson, “Theosis,” in Dialog: A Journal of Theology 32 (St. Paul, Minn: 1993): 108-112, at page 112.)
Catholic scholar Hans Kung has even suggested that the Pelagian affair caused Augustine to replace the earlier deification theory with the doctrine of grace; Orthodox scholar Paul Evdokimov agrees. (Hans Kung, Justification. The Doctrine of Karl Barth and a Catholic Reflection (Westminster Press 1981; 1st German 1957) ):
Frederick W. Norris, a member of the Church of Christ, and professor of Church History at Emmanuel School of Religion in Tennessee, wrote that “in a world which yearns for spirituality…Christians ought to speak of deification.” (F. W. Norris, op. cit., 413.)
Robert Rakestraw, writing in the journal of the Evangelical Theological Society, after covering some of the evidence from the Greek fathers, as well as from Luther, and Charles Wesley, then writes: “Perhaps the most obvious deficiency is the terminology itself. To speak of divinization, deification, and human beings ‘becoming God’ seems to violate the historic Christian understanding of the essential qualitative distinction between God and the creation…. The strengths of theosis theology outweigh these weaknesses, however. The most significant benefit is that the concept as a whole, if not the specific terminology, is Biblical.” (Rakestraw, op. cit., 266-7.)