Short answer, I think those authors derived the concept from their source materials --- in the Jewish scriptures in the Old Greek.
The terms “hell” and “hades” and "sheol" and all the other various Hebrew, Greek and English terms used for such a realm present a complex of connotations for which books have been written. My discussion here is intended to encompass a very wide representation of that underworld realm.
I’ll begin with 1 Peter because verses 3:18-19 are often the centerpiece for discussions of such a descent by the risen spirit of Jesus Christ.
The Book of Isaiah was central to the development of early Christian thought. The author of 1 Peter included 7 direct citations and at least 4 clear allusions from Isaiah. The author of 1 Peter used Isaiah as source material and as a “witness” to Jesus Christ, examples ---
As a chosen and precious cornerstone lain in Zion (1 Peter 2:6 and Isaiah 28:16)
As a stumbling stone and rock of offence (1 Peter 2:8 and Isaiah 8:14)
He committed no sin and no deceit was found in his mouth (1 Peter 2:22 and Isaiah 53:9)
He bore our sins (1 Peter 2:24 and Isaiah 53:4)
By his stripes you are healed (1 Peter 2:24 and Isaiah 53:5)
And the passage often used to demonstrate a descent into the realm of the dead ---
1 Peter | Isaiah (LXX) |
Because Christ also suffered once for sins, the righteous for the unrighteous, so that He might bring you to God, having been put to death indeed in the flesh, but having been made alive in the spirit, in which also having gone, He preached to the spirits in prison (φυλακῇ). (1 Peter 3:18-19) For to this end the gospel was proclaimed even to the dead, so that they might be judged indeed according to men in the flesh, but they might live in the spirit according to God. (1 Peter 4:6) |
… I gave you for a covenant of a race, for a light of nations; to open the eyes of the blind, to lead out of bonds ones being tied; from out of the house of prison (φυλακής) and ones sitting in darkness. (Isaiah 42:6-7) Spirit of the LORD is upon me, because he anointed me to announce good news to the poor. He has sent me to heal the ones being broken in the heart; to proclaim a release to captives and recovery of sight to the blind. (Isaiah 61:1) |
I think these passages in 1 Peter are an expansion of this passage in Ephesians, which was derived from Psalms ---
Ephesians | Psalms (LXX) |
Therefore it says: "Having ascended on high, He led captive captivity, and gave gifts to men." Now what is "He ascended," except that He also descended into the lower regions of the earth? The One having descended is also the same one having ascended above all the heavens, so that He might fulfill all things. (Ephesians 4:8-10) |
You ascended the height; you captured captivity; you received gifts by men … Blessed be the LORD day by day, for you greatly prospered us, O God of our deliverances … even the LORD delivering the ones at the outer reaches of death. (Psalm 68:18-20, note 67:19-21 in some versions) |
All the elements were there in the Jewish scriptures for the creative hands and creative minds of the early Christian writers who found such an event useful in their works.
So why did Jesus Christ descend into the underworld on a redemptive mission? Because the source materials said he did.
robert j