24 What will then be the glory of faith? What the punishment of faithlessness? When the day of judgment shall come, what joy of believers, what sorrow of unbelievers; that they should have been unwilling to believe here, and now that they should be unable to return that they might believe! An ever-burning Gehenna will burn up the condemned, and a punishment devouring with living flames; nor will there be any source whence at any time they may have either respite or end to their torments.
Souls with their bodies will be reserved in infinite tortures for suffering. Thus the man will be for ever seen by us who here gazed upon us for a season; and the short joy of those cruel eyes in the persecutions that they made for us will be compensated by a perpetual spectacle, according to the truth of Holy Scripture, which says, “Their worm shall not die, and their fire shall not be quenched; and they shall be for a vision to all flesh.” Anti again: “Then shall the righteous men stand in great constancy before the face of those who have afflicted them, and have taken away their labours.
When they see it, they shall be troubled with horrible fear, and shall be amazed at the suddenness of their unexpected salvation; and they, repenting and groaning for anguish of spirit, shall say within themselves, These are they whom we had some time in derision, and a proverb of reproach; we fools counted their life madness, and their end to be without honour. How are they numbered among the children of God, and their lot is among the saints! Therefore have we erred from the way of truth, and the light of righteousness has not shined upon us, and the sun rose not on us.
We wearied ourselves in the way of wickedness and destruction; we have gone through deserts where there lay no way; but we have not known the way of the Lord. What has pride profited us, or what good has the boasting of riches done us? All those things are passed away like a shadow.” The pain of punishment will then be without the fruit of penitence; weeping will be useless, and prayer ineffectual. Too late they will believe in eternal punishment who would not believe in eternal life.
Source: The Treatises of Cyprian (New Advent)