Do you like difficult grammar and long sentences? Do you prefer that your readings are slow and demand a second (or third) pass? Then Peter is your guy here in the midst of his letter. It can get a little tricky.
What is clear, though, is that he’s talking to a group of churches that are facing growing persecution. “Suffering” is a constant theme so far. Peter is working out how suffering relates to what we believe about Jesus. If you have heard of the victory that Christ has secured for his people and how he has now ascended and is seated on the throne, what do you make of the suffering that hasn’t lessened, but rather is increasing? Is that to be expected?
Peter is trying to deal with this throughout. What God has done in Jesus is big—and goes back before the world was made. God has had a plan and still has one, so do not lose hope when things are hard. Suffering does not negate God’s plan. In fact, it is present in his plan, not the least in Jesus himself. Jesus suffered, was rejected, and even put to death. So do not assume suffering has no part in the Christian life. But take comfort knowing you are like Jesus in that regard. In those trying times put you hope in Jesus who is able to work for good through suffering. God works through it for others, who we are to bless when they curse, not return evil with evil.
Then this theme of suffering extends beyond this life, and clarity gets a little murky in 1 Peter 3 and 4.
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, in which he went and proclaimed to the spirits in prison, because they formerly did not obey, when God’s patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water. Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ, who has gone into heaven and is at the right hand of God, with angels, authorities, and powers having been subjected to him. (1 Peter 3:18-22 ESV)
And:
For this is why the gospel was preached even to those who are dead, that though judged in the flesh the way people are, they might live in the spirit the way God does. (1 Peter 4:6 ESV)
Christ, or the Spirit, preaching to spirits? Preaching to them in prison, or before they were imprisoned? In the time of Noah, or now after their disobedience? Just another super easy passage. Then in chapter four, there’s a preaching to the dead after they are judged? That doesn’t sound like what we read elsewhere or confess as the church? What’s going on?

To do our best at understanding difficult passages, we must hold closely what is already clear in 1 Peter. He’s addressing suffering in the church. Does suffering have victory when it comes to death? No, Christ suffered and was even put to death. But the result is bringing us to God and making us alive in the spirit. Suffering is not the end for Christ has the victory. It seems here Peter is illustrating this point with the example of suffering in the time of Noah, when evil spirits were a cause. Jesus, who was put to death in the flesh, but was raised in the spirit, goes to proclaim this victory to those evil spirits. Then Noah is the example for us. Hold fast to God, even with opposition and suffering around you. Noah committed himself to God and that was evident by his entering the ark, remaining safely in the waters of the flood. He persevered. We are likewise to commit, persevere in the face of suffering, and baptism by water is a sign for us.
In chapter four again a concern is suffering and death and Peter assures the church that Christ still has the victory. The gospel was preached to those who are now dead, and even though they suffered in this life of flesh and were judged by the world, we know there is more. Death does not end God’s victory or hold back his reach. The world may wield its power and threaten death, but in Jesus there is victory. There is life in the Spirit that no suffering can touch. Hope in Jesus is not only for this life, but for all eternity.