I was just wondering what the reason our resident Christians would give for the reason for this action by Christ. How does it fit in with your theology?
The Jewish view of Sheol (the place of the dead) was that it is divided into two sections, The upper half of Sheol was the place where the righteous dead went awaiting their release into God's immediate presence. (In Christian thinking this was possible once Christ had paid the true price for atonement of sins).
The lower half of Sheol was the abode of the unrighteous dead awaiting their final judgement. From the text in Peter we would also conclude that it was likewise the abode of a number of evil spirits or demons, who had been locked up and prohibited from roaming the earth. They were the agents of evil who had been responsible, at the time of the flood, for seducing mankind away from God until the stage was reached (with the exception of Noah) where the earth become such a wicked place that 'every inclination of man's heart was only evil all the time (Gen 6:5).
When Jesus descended into Sheol He accomplished two things. First those in the upper half of Sheol were released from their period of waiting and ascended with Jesus to glory. As we find in Ephesians 4:8, 'When He ascended on high He led a host of captives -i.e those in captivity in the upper half of Sheol. The upper half of Sheol is now empty as all the righteous dead subsequent to Calvary are taken straight to glory.
Secondly Jesus addressed the evil spirits mentioned above. Many translations (including the KJV) state that Jesus 'preached' to them but I do not think this to be a very good translation. The word can also mean to proclaim and I think the preferred translation, as used by the ESV, is that He, 'made proclamation to the spirits in prison'. An analogy would be a victorious Roman general entering a captured city and proclaiming his victory, their defeat and the consequences thereof. So Jesus would have proclaimed to the forces of evil His total victory over sin, death and evil and that their final demise was now certain. All that was left was some mopping up operations.
I do not subscribe to the view that Jesus preached to the souls of the unrighteous dead to allow them a second opportunity to find salvation. Much as this might sound an attractive idea it would be inconsistent with the overall thrust of Scripture.