John Calvin Commentary 1 Peter 3:18

"Because Christ also suffered for sins once, 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 (ASV)

For Christ also It is another comfort that if, in our afflictions, we are conscious of having done well, we suffer according to the example of Christ; and from this it follows that we are blessed. At the same time, he proves from the design of Christ’s death that it is by no means consistent with our profession that we should suffer for our evil deeds. For he teaches us that Christ suffered in order to bring us to God. What does this mean, except that we have been consecrated to God in this way by Christ’s death, that we may live and die to him?

There are, then, two parts in this sentence: the first is that persecutions ought to be borne with resignation because the Son of God shows the way to us; and the other is that since we have been consecrated to God’s service by the death of Christ, it is fitting for us to suffer, not for our faults, but for righteousness' sake.

Here, however, a question may be raised: Does God not chastise the faithful whenever he allows them to be afflicted? To this I answer that it indeed often happens that God punishes them according to what they deserve; and this is not denied by Peter. But he reminds us what a comfort it is to have our cause connected with God. And how God does not punish sins in those who endure persecution for the sake of righteousness, and in what sense they are said to be innocent, we shall see in the next chapter.

Being put to death in the flesh Now this is a great thing that we are made conformed to the Son of God when we suffer without cause; but there is added another consolation: that the death of Christ had a blessed outcome, for though he suffered through the weakness of the flesh, he nevertheless rose again through the power of the Spirit. Then the cross of Christ was not detrimental, nor his death, since life obtained the victory.

This was said (as Paul also reminds us in 2 Corinthians 4:10) so that we may know that we are to bear in our body the dying of Christ, in order that his life may be manifested in us. Flesh here means the outward man, and Spirit means the divine power by which Christ emerged from death a conqueror.