A note of caution:
The interpretation of 1 Peter 3:18-20 as given by the Church Fathers appears to entirely misunderstand the text.
#1 Failure of the early Church Fathers to correctly interpret 1 Peter 3:19 The early Church Fathers entirely misunderstood the meaning of “spirits in prison” (1 Peter 3:19). From the second century to Augustine in the fifth century, the prevailing notion was that Jesus was actively preaching in Hades to those who had died during Noah’s flood. The “spirits in prison” consequently were the souls of those who died during the flood. But what would be the consequence if the early Church Fathers were absolutely mistaken in their exegesis of his foundational text? What if the “spirits in prison” actually referred to the fallen angels (referred to as “sons of God” in Gen 6:2, 4) who seduced the daughters of men and gave birth to “warriors of renown” (Gen 6:5)?
#2 This text is one of the most complex within the Scriptures. In 2019, by way of defining how the central meaning of this text, Campbell and van Rensburg were prompted to write this: “Few passages in the New Testament have caused greater scholarly deliberation and given rise to so many interpretations and counter-arguments than 1 Peter 3:18-22.”
#3 God did not spare the angels when they sinned, but cast them into TARTAROS (2 Peter 2:4). In the Greek Homeric tradition, Tartaros is the name of the deepest part of the Underworld where Greek gods were held captive and tormented. This was the perfect place where the God of Israel could confine and torment the angels of Gen 6:2-5.
#4 Who were the “spirits in prison” (ἐν φυλακῇ πνεύμασιν)? First, πνεύμασιν (spirits) in the plural is always in reference to angels in the New Testament. Second, it was common Jewish understanding that evil angels were imprisoned (cf. 1 En. 15:8; 21:1-10; Jub 5:6). Third, the interpretation that the disobedient angels in Gen. 6 were imprisoned “was standard in Peter’s day”.
#5 Here is a recent dissertation that can be found online.
Spirits and the Proclamation of Christ : 1 Peter 3:18-22 in its tradition-historical and literary context
Chad Pierce
Published 2009 Durham University PhD dissertation 278 Pages
1 Peter 3:18-22 records Christ’s proclamation to the “imprisoned spirits.” Interpreting this passage has challenged even the most competent exegetes. Earliest interpretations understood these imprisoned spirits as the souls of humans to whom Christ preached during his “harrowing of Hades” between his death and resurrection. Augustine identified them as the humans living prior to the flood who were heralded to by the pre-existent Christ through the person of Noah.
Scholars from the beginning of the twentieth century through the present have read these verses through the lens of the fall of the watchers (Gen 6:1-5) tradition first recorded in the Book of Watchers, thus reckoning these spirits as imprisoned angels. Yet contemporary scholarship has failed to acknowledge the development, conflation, and even multiplicity of the fallen angel sin and punishment myths that are found throughout much of early Jewish and Christian literature.
Fraternally,
Aaron Milavec