For Christ also suffered once for sins, the righteous for the unrighteous, that he might bring us to God, being put to death in the flesh but made alive in the spirit (1 Peter 3:18).
Here is one of the richest, clearest, and briefest New Testament summaries of the work of Christ. Theologians describe the heart of the gospel as penal substitutionary atonement. Jesus paid the penalty for sins (penal) as a substitute in our place (substitutionary) to undo the effects of our sin and restore us to God (atonement, literally “at-one-ment”). This is precisely what we find in this verse: Christ “suffered once for sins [penal], the righteous for the unrighteous [substitutionary], that he might bring us to God [atonement].”
As beautiful as are these gospel truths, the work of Christ accomplished even more. For example, the Devil and his demons are once and for all disarmed. The caring and righteous work of Christ is also an example for us to follow, as Peter himself asserts (2:21). But penal substitution is the fundamental heart of the gospel. The other benefits of Christ’s work all flow from this.
Because of the work of Christ proclaimed in the gospel of grace, we are restored to God. The wreckage we have introduced into our lives through sin and failure and error is canceled. All is forgiven, and one day we will be with Christ in the new earth, in perfect joy.
Adapted from the Gospel Transformation Bible