1 Peter 3:18-22 is one of the most obscure and difficult texts in all of scripture. When did Christ preach to the spirits in prison? What was the content of his preaching? Where did he go to do this preaching? There seems no end to the possible interpretive spins suggested by commentators with regard to this text, and the debate will certainly not be settled in a single blog post.
The difficulty should not distract us from what is clear about the passage, though. Three features of this text give it shape and movement. The passage begins with the suffering of Christ in his death by crucifixion (18). It then moves quickly to the victory of Christ in the resurrction when he was "made alive in the spirit" (18). Peter then brings the text to a resounding climax by declaring the supremacy of Christ over every power as manifest through his exaltation to the right hand of power (22). 1 Peter 3:18-22, then, is a powerful declaration of the comprehensive victory of Christ through his death and resurrection and of his unmatched supremacy in all things through his exaltation to the right hand of God the Father. As a part of that glorious good news, Peter highlights the saving benefit of Christ's resurrection for those who belong to him.
Peter clearly understands the cross as functioning in a substitutionary manner. Christ, the righteous one, died for the unrighteous (18). As one undeserving of suffering, he submitted to suffering in the place of those who rightfully deserved it, namely everyone else. The goal of this suffering was to reconcile estranged humanity to God.
The work of Christ does not end in suffering, though. Peter is happy to celebrate that Jesus was made alive through the agency of the Spirit. Note the trinitarian framework of Peter's soteriology here. Christ died for sins. He was raised by the Spirit. He was exalted to the right hand of God. The fullness of the trinitarian energy is here directed at the saving work accomplished in the death, resurrection, and exaltation of Christ and the movement from suffering to glory.
Despite the interpretive difficulties that come with this brief passage, one thing is clear: the supremacy of Christ in all things. The one who suffered for us now lives and reigns over all things. Salvation comes to us through this one, through his substitutionary death and his all-victorious resurrection (22).
As a result, Peter indicates that we ought to be deeply thankful for our baptism, which marks us out as those who have received the benefit of salvation through Christ's resurrection. Our consciences are clear because Christ suffered the penalty for our transgressions. The saving work is complete because God vindicated Christ by raising him from the dead. Our resurrection hope is certain because the suffering Lord has conquered and reigns supreme over all.