1 Peter 3:19-20 19by whom he also went preaching to the spirits in prison, 20since they formerly did not obey when God’s patience waited in the days of Noah, while the ark was being built, in which a few, that is, eight persons, were brought safely through water.
These are some of the most difficult and obscure verses in the Bible. Interpreters have debated for millennia about what Peter means here. Verse 19 begins with a vague pronoun whom, which could refer to “Spirit” of verse 18. The most natural interpretation is that verse 19 could be a reference to the spiritual existence of Jesus during the time he was physically dead in the tomb, during which he went to imprisoned spirits and preached to them. As the divine Son of God, Jesus existed in some state while dead. So, the interpretation that he went somewhere to continue his ministry would make sense of his divinity.
Verse 20 clarifies that these spirits were disobedient during the time of Noah. These people lived in ignorance and allowed the fleshly results of the sin of Adam and Eve to run rampant and without any check. There was enough light of righteousness at the time that at least Noah and his family walked in it. In the New Testament, when the word preached(ekēryxen) is used, it usually refers to the gospel. This implies that Jesus preached the good news of salvation to the spirits of people who needed freedom because of their entrapment by death and hell. One significant problem with this interpretation is the idea that these people got a second chance after death, which the Bible does not teach anywhere else.
Verse 19 shows an example to the readers of how Jesus went to great lengths to reach the lost, and how God showed much patience in the days of Noah for those who were doing evil. One lesson is how God continues to wait patiently for people to repent (2 Peter 3:9). God was patient with people, but only eight people out of the whole population actually listened. Peter could be merging Jesus’ historical resurrection with the spiritual need of his readers. The past story of Noah and the flood show how the readers’ own suffering can lead to the salvation of those around them. Our ministry in our suffering should be similar to Jesus in his suffering: preach the good news to those who need released from sin. Jesus came to preach good news to those imprisoned (Luke 4:18-19), which is also what the world needs today.