Roman Catholic theology maintains that while eternal punishment and the guilt of moral sin is absolved by the sacrament of penance, the requirement of satisfaction and temporal as opposed to eternal punishment is not. If appropriate satisfaction has not been made for sins committed and absolved in life, then satisfaction must be made after death. Purgatory is not hell, since all the souls in purgatory are on their way to the heavenly Jerusalem, though it is a place of temporal punishment. The Catholic Church has usually appealed to texts such as 2 Maccabees 12:39-45; Matthew 12:31ff.; 1 Corinthians 3:11-15 to support the idea of an intermediate place between heaven and hell, where the unfinished business of earth is settled.
The notion of purgatory appears fairly early in the writings of the Greek Fathers. [[Clement of Alexandria]]* near the end of the second century alludes to the sanctification of deathbed penitents by purifying fire in the next life. Even when the Greek Fathers do not talk about purgatory, they do advocate prayers and eucharistic services on behalf of the dead. The Latin Fathers echo these sentiments. Augustine,* for example, teaches purification through suffering in the afterlife. The medieval doctors systematized and developed the patristic heritage, teaching that the smallest pain in purgatory is greater than the greatest pain on earth, though the souls in purgatory are comforted by the knowledge that they are among the saved and are aided by the prayers and Masses offered for them by the church. The doctrine was developed and popularized by Gregory the Great,* and [[Thomas Aquinas]]* gave the idea greater elaboration.
The Greek Church had difficulty with the final form of the Latin doctrine of purgatory, rejecting the notion of atonement through suffering and the idea of material fire. The Greeks and Latins, however, were able to agree at Florence* (1439) that there is such a place as purgatory, and that prayers for the dead* are both useful and appropriate. In the West, purgatory was questioned and categorically denied by the Protestant Reformers, but was reaffirmed at the [[Council of Trent]].*
See B. Bartmann, Purgatory (1936), and H. Berkhof, Well-Founded Hope (1969).