1 Peter 3:18
Verse 18 is considered “one of the shortest and simplest, and yet one of the richest summaries given in the New Testament of the meaning of the Cross of Jesus” - BKC
For Christ also suffered -- Peter wished to encourage his readers in their suffering by again reminding them that even Christ suffered unjustly because it was God’s will (v. 11). - MSB
Christ suffered -- Some manuscripts read Christ died. • He suffered physical death (literally death in the flesh).
but he was raised to life in the Spirit (or in spirit): Flesh and spirit are often contrasted (e.g., Romans 7:5-6; Romans 8:2-11). Here, flesh stands for ordinary human life; the Spirit stands for the new realm inaugurated through Christ’s death and resurrection. Christ died in the old realm, and came to life in the new realm. NLTSB
Both of these phrases are AORIST PASSIVE PARTICIPLES, which implies a historical event (crucifixion and resurrection, cf. Romans 1:3-4) - Utley
once for all -- (cf. Romans 6:10; Hebrews 9:26, Hebrews 9:28; Hebrews 10:10) is clearly a contrast with the Old Testament yearly sacrifice on the Day of Atonement and declares the complete sufficiency of Christ’s death. -FSB
This is the theme of the book of Hebrews (cf. Romans 6:10; Hebrews 7:17; Hebrews 9:12, Hebrews 9:18, Hebrews 9:26, Hebrews 9:28; Hebrews 10:10). - Utley
the righteous for the unrighteous -- (dikaios hyper adikōn). Christ, the “righteous One” (dikaios), uniquely qualified to die as the substitute for (hyper, “for,” “in place of,” or “instead of”) the “unrighteous ones” (adikōn). - FSB
“The righteous one” may have been a title for Jesus in the early church (cf. Acts 3:14; Acts 7:52; 1 John 2:1, 1 John 2:29; 1 John 3:7). It emphasizes His sinless life (cf. 1 Peter 1:19; 1 Peter 2:22) - Utley
the just for the unjust -- This is another statement of the sinlessness of Jesus (cf. Hebrews 7:26) and of His substitutionary and vicarious atonement. - MSB
in order that -- This is a hina (purpose) clause.
bring us to God -- The divine purpose for Christ’s sacrificial death was man’s reconciliation, to bring people to God.
alive by the Spirit -- This is not a reference to the Holy Spirit, but to Jesus’ true inner life, His own spirit. Contrasted with His flesh (humanness) which was dead for 3 days, His spirit (deity) was alive, lit. “in spirit” (cf. Luke 23:46). - MSB
It is difficult in this passage to determine whether “spirit” should be capitalized (i.e. Holy Spirit) or not (i.e. Jesus’ human spirit). I prefer the latter (as does A. T. Robertson), but F. F. Bruce prefers the former. - Utley
[One thinks that the interpretation of "Spirit" here must flow over into the "by whom" in the next verse to be consistent. WG]