Sacred scripture tells us in Acts 2:27-31:
Because thou wilt not leave my soul in hell, neither wilt thou suffer thine Holy One to see corruption. 28 Thou hast made know
n to me the ways of life; thou shalt make me full of joy with thy countenance. 29 Men and brethren, let me freely speak unto you of the patriarch David, that he is both dead and buried, and his sepulchre is with us unto this day. 30 Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne; 31 **He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption.**
What is this "hell" or hades into which our Lord went? Is it merely the physical grave where his body lay, or is it the supernatural realm of the dead?
Luke 8:28-31 tells us that demons can be cast into "the deep" or the abyss:
When he saw Jesus, he cried out, and fell down before him, and with a loud voice said, What have I to do with thee, Jesus, thou Son of God most high? I beseech thee, torment me not. 29 (For he had commanded the unclean spirit to come out of the man. For oftentimes it had caught him: and he was kept bound with chains and in fetters; and he brake the bands, and was driven of the devil into the wilderness.) 30 And Jesus asked him, saying, What is thy name? And he said, Legion: because many devils were entered into him. 31 And they besought him that he would not command them to go out into the deep.
We see more about this supposed abyss in the book of Revelation. In chapter 9:1-11, we read
And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit (abyss). 2 And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit. 3 And there came out of the smoke locusts upon the earth: and unto them was given power, as the scorpions of the earth have power... 11 And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.
(There are other texts referring to this place of the abyss as a prison for demons)
In Jude 6 and the parallel passage in 2 Peter 2:4, we read
And the angels which kept not their first estate, but left their own habitation, he hath **reserved in everlasting chains under darkness unto the judgment of the great day.** (Jude 6)
For if God spared not the angels that sinned, but cast them down to hell (tartarus), and delivered them into chains of darkness, to be reserved unto judgment (2 Peter 2:4)
Now this word tartarus is defined as the deepest abyss in hades, hence we can confirm that the abyss spoken of in St. Luke and Revelation is identical to this tartarus. Now if tartarus is a place in Hades, we can see a relation between hades, where the soul of Christ departed to after his death, and the abyss/tartarus where the demons are imprisoned. St. Peter connects the two concepts by describing how Christ descended to this prison after his death:
For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: 19 By which also he went and preached unto the spirits in prison; 20 Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water. (1 Peter 3:19)
An important distinction to make, is that our Lord did not so descend into hell as to suffer punishments there, but in order to conquer it and preach the gospel to the damned. This does not exclude his entrance into paradise (c.f. Luke 23:43), and his subsequent "harrowing of hell" where he leads the new and better exodus out of death itself, completely conquering death, hell, and the devil.
St. Paul also describes this descent of Christ into the abyss:
But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:) 7 Or, Who shall descend into the deep (abyss)? (that is, to bring up Christ again from the dead.) (Romans 10:6-7)
Here St. Paul provides the pinnacle of our exegesis, by stating that Christ descended into the abyss, which is the place of the dead, that is hades. He elsewhere states:
Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men. 9 (Now that he ascended, what is it but that he also descended first into the lower parts of the earth? 10 He that descended is the same also that ascended up far above all heavens, that he might fill all things.) (Ephesians 4:8-10)
Hence we affirm with the Apostles creed:
We believe... in Jesus Christ his only Son our Lord, who was conceived by the Holy Ghost, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, dead, and buried. He descended into hell, on the third day he rose again from the dead. He ascended into heaven, and is seated at the right hand of God the Father Almighty. He shall come again to judge the quick and the dead