The noun form of metamorphoō (G3213). Denotes the act or process of transformation — a change in form. Though the noun itself is rare, the concept it represents — spiritual transformation into Christlikeness — is central to New Testament theology.
While the noun form is rare in the Greek NT, the concept of transformation pervades the New Testament. Believers are being transformed into Christ's image (2 Corinthians 3:18), renewed in the spirit of their minds (Ephesians 4:23), and will ultimately be transformed when Christ appears (1 John 3:2). The transfiguration of Jesus on the mountain previews the glory that all believers will share. Transformation is both present (progressive sanctification) and future (glorification).