(1) Why did Jesus descend into hell?In the Apostle's Creed we pray the following:
He suffered under Pontius Pilate,The English word for "hell" used in the Bible is actually two distinct places and has two different ways of being used. In the Apostle's Creed the word means "Hades" which is also known as the Abode of the Dead. This is mentioned in the Bible as the place Christ descends into:
was crucified, died, and was buried.
He descended into hell.
"For Christ also suffered for sins once, the righteous for the sake of the unrighteous, that he might lead you to God. Put to death in the flesh, he was brought to life in the spirit. In it he also went to preach to the spirits in prison, who had once been disobedient while God patiently waited in the days of Noah during the building of the ark, in which a few persons, eight in all, were saved through water." -1 Peter 3: 18-20This is sometimes called the "Limbo of the Fathers". It is neither heaven or hell, but a temporary place that was a kind of holding place for those who would eventually be judged by Christ, but died before Christ came and awaited the Messiah.
The second kind of hell is sometimes referred to as "Gehenna" in the Bible. It is the place or eternal punishment.
The Catechism says the following:
633 Scripture calls the abode of the dead, to which the dead Christ went down, "hell" - Sheol in Hebrew or Hades in Greek - because those who are there are deprived of the vision of God. Such is the case for all the dead, whether evil or righteous, while they await the Redeemer: which does not mean that their lot is identical, as Jesus shows through the parable of the poor man Lazarus who was received into "Abraham's bosom": "It is precisely these holy souls, who awaited their Savior in Abraham's bosom, whom Christ the Lord delivered when he descended into hell." Jesus did not descend into hell to deliver the damned, nor to destroy the hell of damnation, but to free the just who had gone before him.
(2) Why did Satan reject God?Satan rejected God because of his pride. Satan and his demons are all fallen angels who were created with free will and as pure spiritual beings. Therefore, they had the greatest intellects of all creatures. They were given a choice - God or not God. 1/3 of the angels chose to not follow God and they were cast out of heaven. Because they are pure spirit and have such great intellects, their choice was an irrevocable one - it cannot be undone.
John Paul II teaches about the fallen angels in a thorough catechesis on the subject, which I recommend for further reading. Here is a snip:
This "fall", which has the character of rejection of God with the consequent state of "damnation", consists in the free choice of those created spirits who have radically and irrevocably rejected God and his kingdom usurping his sovereign rights and attempting to subvert the economy of salvation and the very order of the entire creation. We find a reflection of this attitude in the words addressed by the tempter to our first parents: "You will become like God" or "like gods" (cf. Gen 3:5). Thus the evil spirit tries to transplant into man the attitude of rivalry, insubordination and opposition to God, which has, as it were, become the motivation of all his existence.
(3) Why did Jesus say "My God my God why have you forsaken me?"Here are the two places where the Bible tells us Jesus says these words, while on the cross:
"And about three o'clock Jesus cried out in a loud voice, "Eli, Eli, lema sabachthani?" 28 which means, "My God, my God, why have you forsaken me?"" - Matt 28:46Every Jew at the time of Jesus would have known why Jesus was saying this. He is reciting the first line of Psalm 22 - "My God, my God, why have you abandoned me? Why so far from my call for help, from my cries of anguish?". Thus, he wants them to think of this Psalm of anguish which King David wrote, which also foreshadows Jesus death.
"And at three o'clock Jesus cried out in a loud voice, "Eloi, Eloi, lema sabachthani?" which is translated, "My God, my God, why have you forsaken me?"" - Mark 15:34
Some have said that Jesus was no longer God at this moment, but this idea has been rejected by the Church. Jesus cannot separate his two natures (human and divine), they will always be joined together in the person of Christ. So, why cry out this Psalm? Two reasons.
1 - Just as the crucifixion is terrible and sad, so is the first part of Psalm 22. But, suffering and death do not have the final word. We have the Resurrection and the end of Psalm 22 ends triumphantly. A snip of the Psalm to get a sense of what is happening:
But you, LORD, do not stay far off; my strength, come quickly to help me. Deliver me from the sword, my forlorn life from the teeth of the dog. Save me from the lion's mouth, my poor life from the horns of wild bulls. Then I will proclaim your name to the assembly; in the community I will praise you: "You who fear the LORD, give praise! All descendants of Jacob, give honor; show reverence, all descendants of Israel! For God has not spurned or disdained the misery of this poor wretch, Did not turn away from me, but heard me when I cried out. - Psalm 22: 20-25The second reason he cried out to The Father is because he was suffering so horribly and was united to all of humanity as he cried out as every other human would.
Thus, the Catechism says:
603 Jesus did not experience reprobation as if he himself had sinned. But in the redeeming love that always united him to the Father, he assumed us in the state of our waywardness of sin, to the point that he could say in our name from the cross: "My God, my God, why have you forsaken me?" Having thus established him in solidarity with us sinners, God "did not spare his own Son but gave him up for us all", so that we might be "reconciled to God by the death of his Son".I hope this helps.