The spirits in prison is a recurrent minor subject in the writings of Christianity.
The subject takes its starting point from a Bible reference:
According to Augustine the spirits are the unbelieving contemporaries of Noah, to whom the spirit of Christ in Noah, preached, or to whom pre-existent Christ himself preached.
Unitarians, such as Thomas Belsham, considered that the spirits in prison were simply Gentiles in the prison of ignorance to whom Christ preached through his apostles.
Wayne Grudem (1988) identifies five commonly held views on the interpretation of this verse:
These views revolve around the identity of the spirits in prison, the time in which the preaching took place, and the content of the preaching.
This is also found in Thomas Aquinas; Summa Theologica (3,52,2). A variant of this view is the view of the Rev. Archibald Currie (1871) that Christ through Noah preached to "the spirits in prison ;" meaning the eight persons interned in the Ark as in a place of protection.
The Anglican Edward Hayes Plumptre, Dean of Wells, in The Spirits in Prison starting from the verse in Peter argued for revival in the belief in the harrowing of Hell and the spirit of Christ preaching to the souls of the dead in Hades while his body was in the grave.
Some disagree with this interpretation of I Peter, citing 2 Peter 2:4-5, implying that the spirits were disobedient angels, not dead people. However, Peter already mentioned "angels" in 1:12, so if Peter wanted us to think they were angels, surely he would have used that word. Support for the idea that "spirits" refers to people comes from several other New Testament texts, such as Luke 23:46, James 2:26, and Hebrews 12:23. The fact that Peter says a few verses later that the dead were evangelized in 4:6 points us to the fact that we are most likely dealing with dead people not fallen angels. After all, angels don't die.
This is a variant of the harrowing of Hell idea, except that Christ only proclaims triumph.
This view originates with Robert Bellarmine (1586) and has been followed by some Catholic Church commentators in relation to a belief in Purgatory.