Jesus said to his disciples: ‘When the Son of Man comes in his glory, escorted by all the angels, then he will take his seat on his throne of glory. All the nations will be assembled before him and he will separate men one from another as the shepherd separates sheep from goats. He will place the sheep on his right hand and the goats on his left.
‘Then the King will say to those on his right hand, “Come, you whom my Father has blessed, take for your heritage the kingdom prepared for you since the foundation of the world. For I was hungry and you gave me food; I was thirsty and you gave me drink; I was a stranger and you made me welcome; naked and you clothed me, sick and you visited me, in prison and you came to see me.” Then the virtuous will say to him in reply, “Lord, when did we see you hungry and feed you; or thirsty and give you drink? When did we see you a stranger and make you welcome; naked and clothe you; sick or in prison and go to see you?” And the King will answer, “I tell you solemnly, in so far as you did this to one of the least of these brothers of mine, you did it to me.”
‘Next he will say to those on his left hand, “Go away from me, with your curse upon you, to the eternal fire prepared for the devil and his angels. For I was hungry and you never gave me food; I was thirsty and you never gave me anything to drink; I was a stranger and you never made me welcome, naked and you never clothed me, sick and in prison and you never visited me.” Then it will be their turn to ask, “Lord, when did we see you hungry or thirsty, a stranger or naked, sick or in prison, and did not come to your help?” Then he will answer, “I tell you solemnly, in so far as you neglected to do this to one of the least of these, you neglected to do it to me.”
‘And they will go away to eternal punishment, and the virtuous to eternal life.’
Source: Jerusalem Bible
Catechism of the Catholic Church
1033 We cannot be united with God unless we freely choose to love him. But we cannot love God if we sin gravely against him, against our neighbor or against ourselves: “He who does not love remains in death. Anyone who hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.” Our Lord warns us that we shall be separated from him if we fail to meet the serious needs of the poor and the little ones who are his brethren. To die in mortal sin without repenting and accepting God’s merciful love means remaining separated from him for ever by our own free choice. This state of definitive self-exclusion from communion with God and the blessed is called “hell.”
1034 Jesus often speaks of “Gehenna” of “the unquenchable fire” reserved for those who to the end of their lives refuse to believe and be converted, where both soul and body can be lost. Jesus solemnly proclaims that he “will send his angels, and they will gather . . . all evil doers, and throw them into the furnace of fire,” and that he will pronounce the condemnation: “Depart from me, you cursed, into the eternal fire!”
1035 The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, “eternal fire.” The chief punishment of hell is eternal separation from God, in whom alone man can possess the life and happiness for which he was created and for which he longs.
1036 The affirmations of Sacred Scripture and the teachings of the Church on the subject of hell are a call to the responsibility incumbent upon man to make use of his freedom in view of his eternal destiny. They are at the same time an urgent call to conversion: “Enter by the narrow gate; for the gate is wide and the way is easy, that leads to destruction, and those who enter by it are many. For the gate is narrow and the way is hard, that leads to life, and those who find it are few.”
Since we know neither the day nor the hour, we should follow the advice of the Lord and watch constantly so that, when the single course of our earthly life is completed, we may merit to enter with him into the marriage feast and be numbered among the blessed, and not, like the wicked and slothful servants, be ordered to depart into the eternal fire, into the outer darkness where “men will weep and gnash their teeth.”
1037 God predestines no one to go to hell; for this, a willful turning away from God (a mortal sin) is necessary, and persistence in it until the end. In the Eucharistic liturgy and in the daily prayers of her faithful, the Church implores the mercy of God, who does not want “any to perish, but all to come to repentance”:
Father, accept this offering
from your whole family.
Grant us your peace in this life,
save us from final damnation,
and count us among those you have chosen.
For the leader. Of David, the servant of the LORD, who sang to the LORD the words of this song after the LORD had rescued him from the clutches of all his enemies and from the hand of Saul.
He said: I love you, LORD, my strength,
LORD, my rock, my fortress, my deliverer, My God, my rock of refuge, my shield, my saving horn, my stronghold!
Praised be the LORD, I exclaim! I have been delivered from my enemies.
The breakers of death surged round about me; the menacing floods terrified me.
The cords of Sheol tightened; the snares of death lay in wait for me.
In my distress I called out: LORD! I cried out to my God. From his temple he heard my voice; my cry to him reached his ears.
The earth rocked and shook; the foundations of the mountains trembled; they shook as his wrath flared up.
Smoke rose in his nostrils, a devouring fire poured from his mouth; it kindled coals into flame.
He parted the heavens and came down, a dark cloud under his feet.
Mounted on a cherub he flew, borne along on the wings of the wind.
He made darkness the cover about him; his canopy, heavy thunderheads.
Before him scudded his clouds, hail and lightning too.
The LORD thundered from heaven; the Most High made his voice resound.
Source: The New American Bible