For our part, we recognize that even in this life some punishments are purgatorial--not, indeed, to those whose life is none the better, but rather the worse for them, but to those who are constrained by them to amend their life.The quote above is from the latter years of Saint Augustine's life (426 - he died in 430). The passage reveals his fully developed theology. Here he makes the Catholic distinction between temporal punishment and eternal punishment and states that the former my be suffered after death. These post-mortem sufferings are not those eternal pains of Hell, but a different kind of punishment: purgatorial pains.
All other punishments, whether temporal or eternal, inflicted as they are on every one by divine providence, are sent either on account of past sins, or of sins presently allowed in the life, or to exercise and reveal a man's graces. They may be inflicted by the instrumentality of bad men and angels as well as of the good. For even if any one suffers some hurt through another's wickedness or mistake, the man indeed sins whose ignorance or injustice does the harm; but God, who by His just though hidden judgment permits it to be done, sins not.
But temporary punishments are suffered by some in this life only, by others after death, by others both now and then; but all of them before that last and strictest judgment. But of those who suffer temporary punishments after death, all are not doomed to those everlasting pains which are to follow that judgment; for to some, as we have already said, what is not remitted in this world is remitted in the next, that is, they are not punished with the eternal punishment of the world to come.
Saint Augustine City of God, 21, 13 (emphasis mine)
Augustine's words, not mine.
Saint Augustine goes on to explain the need for prayers for the dead and sheds more light on the temporary post-mortem sufferings of the "regenerated":
For some of the dead, indeed, the prayer of the Church or of pious individuals is heard; but it is for those who, having been regenerated in Christ, did not spend their life so wickedly that they can be judged unworthy of such compassion, nor so well that they can be considered to have no need of it.Here we have Augustine's approval of prayers for the dead. We also have him citing Matthew 12:32 as proof that sins can be remitted not only in this life, but in the world to come. You may remember from an earlier post this month that Saint Gregory the Great cited the same verse in Matthew as teaching the existence of a purgatorial state after death (visit post: Gregory the Great on Purgatory).
As also, after the resurrection, there will be some of the dead to whom, after they have endured the pains proper to the spirits of the dead, mercy shall be accorded, and acquittal from the punishment of the eternal fire. For were there not some whose sins, though not remitted in this life, shall be remitted in that which is to come, it could not be truly said, "They shall not be forgiven, neither in this world, neither in that which is to come.' But when the Judge of quick and dead has said, 'Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world,' and to those on the other side, 'Depart from me, ye cursed, into the eternal fire, which is prepared for the devil and his angels,' and 'These shall go away into eternal punishment, but the righteous into eternal life,' it were excessively presumptuous to say that the punishment of any of those whom God has said shall go away into eternal punishment shall not be eternal, and so bring either despair or doubt upon the corresponding promise of life eternal."
Saint Augustine City of God 21, 24
If you're interested in Saint Paul's argument for purgatory ("saved through fire") please visit my other site - The Catholic Perspective on Paul.