It was part of God’s plan of redemption for Jesus to spend three days and nights in the heart of the earth (Matthew 12:39, 40). It was there that He demonstrated His total conquest of death. Not only did He not experience corruption himself, but He released the spirits of the righteous dead to come with Him into His Father’s presence (Acts 2:31).  

 Jesus paved the way for us to enter directly into God’s presence at death. 

Wherefore he saith. When he ascended up on high, he led captivity captive, and gave gifts unto men. (Now that he ascended, what is it but that he also descended first into the lower parts of the earth? He that descended is the same also that ascended up far above all heavens, that he might fill all things) (Ephesians 4:8-10).  

 Jesus removed the sting of death, that we need not sorrow as those outside Christ.

O death, where is thy sting? O grave, where is thy victory? The sting of death is sin; and the strength of sin is the law. But thanks be to God, which giveth us the victory through our Lord Jesus Christ (1 Corinthians 15:55-57).  

But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him (1 Thessalonians 4:13, 14).  

 Jesus brought the gospel to those who had died before His time.

For Christ also hath once suffered/or 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: By which also he went and preached unto the spirits in prison; Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing … (1 Peter 3:18-20).  

 Jesus defeated all the powers of Satan and his hosts and became Head of the Church.

Which he wrought in Christ, when he raised him from the dead, and set him at his own right hand in the heavenly places, far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come: And hath put all things under his feet, and gave him to be the head over all things to the church (Ephesians 1:20-22).  

 Jesus destroyed the bondage we experience through the fear of death.

Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil; And deliver them who through fear of death were all their lifetime subject to bondage (Hebrews 2:14,15).