To answer this question, we need to take a look at 2 Peter and Jude, but a little bit of background is going to be necessary first. Some of the strange sayings in 2 Peter and Jude come from the story communicated in 1 Enoch. This means that while 1 Enoch is not a part of the Bible, it still informed the Bible writers. So if they saw it as having some benefit even in its non-biblical state, then maybe we can too. After all, the Bible tells us to check out plenty of non-canonical books for more information on Biblical topics (Josh 10:13; Num 21:14; 1 Ki 11:41; 14:19, 29; 2 Ch 9:29 to name a few).
It’s there in books like 1 Enoch that we find elaboration on the strange story communicated in Genesis 6:4—that is, that the supernatural sons of god had sex with the natural daughters of men and created giants called the Nephilim. That’s about all the background we have on the Nephilim in Genesis, but the popular intertestamental Jewish book, 1 Enoch, goes into fine detail about the event. From this Jewish perspective, the sons of God were a group of 200 angels that turned against God and in their lust, made a pact to take human wives. Their wives gave birth to giants and they brought incredible sin into the world.
God eventually pronounces judgment on the sons of God and has them imprisoned in the pit (like the pit we see in Revelation). Enoch is then sent to the watcher angels in the pit with a message: They may no longer go up to heaven and they will be bound with the chains of earth for all eternity (1 En 14:5). Furthermore, their Nephilim children will die in the flood of Noah’s time (1 En 12:5-6) and their disembodied souls will live on as demons (1 En 15:8-9).
We might make this all out to be fantasy, but then we find the story referenced in the New Testament as well; for the fate of the fallen angels of 1 Enoch are mentioned by both Peter and Jude (2 Pe 2:4-5, 9-10; Jude 6).
Okay, so what does this all have to do with Jesus? Well, Peter taught that after Jesus died and was made alive in the spirit, 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” (1 Pe 3:19-20). This verse has left many people scratching their heads, but now we see it in the light of 1 Enoch—that is to say, just as Enoch went and proclaimed to the fallen angels that their sentence would not change, so Jesus has gone and done the same. They have lost, will lose, and the day of judgment is coming.
Without considering 1 Enoch many have come to believe Peter was saying that Jesus went and evangelized to human spirits that died before His time and offered salvation to them; but now we know that is not the case. Spirits is a word interchangeably used with angels in Jewish literature, and these spirits in prison are the watcher angels of old that created the Nephilim. Jesus is telling them that their sentence is still the same, just like Enoch did when the watchers asked him to ask God to let them off the hook. As Bible scholar and semitics language expert Michael Heiser points out, Jesus is the new Enoch:
Just as Jesus was the second Adam for Paul, Jesus is the second Enoch for Peter. Enoch descended to the imprisoned fallen angels to announce their doom. First Peter 3:14–22 has Jesus descending to these same “spirits in prison” to tell them they were still defeated, despite his crucifixion. God’s plan of salvation and kingdom rule had not been derailed—in fact, it was right on schedule. The crucifixion actually meant victory over every demonic force opposed to God. This victory declaration is why 1 Peter 3:14–22 ends with Jesus risen from the dead and set at the right hand of God—above all angels, authorities and powers. The messaging is very deliberate, and has a supernatural view of Genesis 6:1–4 at its core. (Heiser, The Unseen Realm, p. 339)
This is an adapted excerpt from my book, The Rush and the Rest: The Holy Spirit and the Supernatural World.