Summary: Who were the spirits in prison? Did God forsake Jesus on the cross?
Did Jesus Suffer in Hell? (Part 2)
Preaching to the spirits in prison
18 For Christ also suffered once for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh but made alive by the Spirit,
19 by whom also He went and preached to the spirits in prison,
20 who formerly were disobedient, when once the Divine longsuffering waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight souls, were saved through water.
Who were the spirits in prison? Some believe it was fallen angels. I suppose it is possible that Jesus would proclaim His victory to the principalities that tried to hinder God’s plan, but I don’t believe this is what is being communicated here. This passage says that Jesus preached to those who were formerly disobedient while God patiently waited. Fallen angels (or demons) were not formerly disobedient – they are presently the way they have been since their fall. They will not change and cannot be redeemed according to scripture. 1 Peter 4 (quickview)  gives more information:
5 They will give an account to Him who is ready to judge the living and the dead.
6 For this reason the gospel was preached also to those who are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.
The Bible first identifies those God waited for in the days of Noah and now others are included. Jesus preached the gospel to those who are dead. They also will live according to God in the spirit just as we will. I believe that this is the Old Testament saints. Look at
50 And Jesus cried out again with a loud voice, and yielded up His spirit.
52 and the graves were opened; and many bodies of the saints who had fallen asleep were raised;
53 and coming out of the graves after His resurrection, they went into the holy city and appeared to many.
I want to compare this to Jesus’ explanation of the uncompassionate rich man and the beggar. Daily the rich man passed by the needy beggar and never even offered a crumb. Jesus continues the illustration in Luke 16 (quickview) :
22 "So it was that the beggar died, and was carried by the angels to Abraham’s bosom. The rich man also died and was buried.
23 "And being in torments in Hades, he lifted up his eyes and saw Abraham afar off, and Lazarus in his bosom.
24 "Then he cried and said, ’Father Abraham, have mercy on me, and send Lazarus that he may dip the tip of his finger in water and cool my tongue; for I am tormented in this flame.’
25 "But Abraham said, ’Son, remember that in your lifetime you received your good things, and likewise Lazarus evil things; but now he is comforted and you are tormented.
26 ’And besides all this, between us and you there is a great gulf fixed, so that those who want to pass from here to you cannot, nor can those from there pass to us.’
In these passages, Jesus revealed that Hades had two sections. On one side there was torment and on the other side the saints were at rest. Now if we take this information back to the passage of Jesus preaching to the spirits in prison, we can get a better understanding. Keep in mind that the Old Testament Saints were waiting for their redemption as well. By faith they kept the law and trusted in God’s redemption that was yet to be revealed. The Bible pointedly states that the sacrifices of bulls and rams cannot take away sin. Until Jesus died on the cross, God’s people were still in bondage to sin. They were not tormented because they were credited with righteousness because of their faith, but they could not be justified until the debt owed to sin was paid. An animal sacrifice cannot pay that debt. Jesus alone paid that debt. Once He died, their redemption was preached and they were released from prison. When He rose, the Bible says that they were no longer in Hades. A sinful man or woman cannot come into God’s presence. Therefore, I believe that the Old Testament saints could not enter their final rest until they were justified by Christ on the cross. Until that time, they were in prison waiting for Messiah to come. They were not in torment and were not being punished, but they were still under the debt of sin. Jesus stated that He came to set the captives free. Bondage is from sin, but freedom comes only through the completed work of Christ on the cross.