What is purgatory, and is it in the Bible?

The teaching. "All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven" (CCC 1030). Purgatory is not a second chance, and it is not a lesser hell. Everyone in purgatory is saved and going to heaven.

Why it must exist. "Nothing unclean shall enter" heaven (Rev 21:27), yet most of us die with attachments to sin, unrepented venial sins, and unhealed wounds. Either God lowers the bar for heaven, or He finishes the work of making us holy. Purgatory is that finishing.

Scripture. 2 Maccabees 12:44-46 praises prayer for the dead "that they might be freed from this sin," which is pointless if the dead are already in heaven or hell. Jesus speaks of a sin that will not be forgiven "in this age or in the age to come" (Mt 12:32), implying some are forgiven after death. St. Paul says a person's work will be tested by fire, and "if someone's work is burned up, that one will suffer loss; the person will be saved, but only as through fire" (1 Cor 3:13-15). Jesus warns that you will not be released "until you have paid the last penny" (Mt 5:26).

Tradition. Christians prayed for the dead from the beginning; the catacombs are full of such inscriptions. St. Monica asked Augustine to remember her at the altar. The Church defined the doctrine at Lyons (1274), Florence (1439), and Trent (1563).

What we do. We pray for the souls in purgatory, offer Masses, and gain indulgences for them (CCC 1032). It is a work of mercy for people who cannot help themselves and who will, once in heaven, pray for us.