“Conformed to the image of his Son” (Romans 8:29) is the ultimate goal of God’s electing and saving purpose, so surely and securely to be accomplished that Paul can speak of it in a past tense as something already made good (Romans 8:30, see also the proviso in Romans 8:17). The details of this final working out of divine plans for the church are given in our passage.
The time of it is related to Christ’s return and glorification (2 Thessalonians 1:10), placed at some future date when the events of 1 Thessalonians 4:13-18 will occur. This matches Paul’s reference in Philippians 3:21. His appearing is described as instantaneous (15:52) with the trumpet call of Matthew 24:31 showing the calling together of God’s elect people; the holy dead will be raised and glorified; and the church of the end time on earth will be transformed and united with the church triumphant in the Lord’s presence.
Paul’s immediate interest in these verses concentrates on the surviving Christian generation of that time, and is expressed in the phrase “we shall … be changed” (15:51), ie transformed by the assumption of a spiritual body (15:44). 15:53 amplifies this change by the thought of the “putting on” of immortality as a covering, so changing the believer’s earthly form. Where else does Paul use this imagery (2 Corinthians 5:24)? And that new life marks the transition from the old order of sin and death in Adam to the new age of which prophecy (Isaiah 25:8; Hosea 13:14) had spoken. Both texts are adapted, however, to Paul’s purpose. How?
The link between sin-law-death in Romans 5:12ff. explains the presence of these terms in 15:56-57. The logic in both passages is clear and incisive. A broken law requires the exaction of a penalty; this penalty is death; and death assumes its awful character, not as a biological necessity (Hebrews 9:27), but as the “sacrament of sin,” (Denney). It is the outward and visible sign of a spiritual disgrace.
In a significant turning point, however, characterized by Paul’s “but” (15:57; see also Romans 5:15), a fresh start is offered to humanity by the announcement of God’s redeeming act in Christ. Hence, the last word is one of victory (three times repeated in three neighboring verses).
Paul now completes the thought. In light of God’s action and the church’s new life in the risen Christ, a call to perseverance and service rings out (15:58). Paul’s teaching on salvation always has to be worked out; indeed without the presupposition of our standing in Christ, a summons to a changed life would be a counsel of despair and a call to barren moralism: eg Philippians 2:5-11 is followed by 2:12-13.
