Ratzinger in Spe Salvi:
“Saint Paul, in his First Letter to the Corinthians, gives us an idea of the differing impact of God’s judgement according to each person’s particular circumstances. He does this using images which in some way try to express the invisible, without it being possible for us to conceptualize these images—simply because we can neither see into the world beyond death nor do we have any experience of it. Paul begins by saying that Christian life is built upon a common foundation: Jesus Christ. This foundation endures. If we have stood firm on this foundation and built our life upon it, we know that it cannot be taken away from us even in death. Then Paul continues: “Now if any one builds on the foundation with gold, silver, precious stones, wood, hay, straw—each man’s work will become manifest; for the Day will disclose it, because it will be revealed with fire, and the fire will test what sort of work each one has done. If the work which any man has built on the foundation survives, he will receive a reward. If any man’s work is burned up, he will suffer loss, though he himself will be saved, but only as through fire” (1 Cor 3:12-15). In this text, it is in any case evident that our salvation can take different forms, that some of what is built may be burned down, that in order to be saved we personally have to pass through “fire” so as to become fully open to receiving God and able to take our place at the table of the eternal marriage-feast.
“47. Some recent theologians are of the opinion that the fire which both burns and saves is Christ himself, the Judge and Saviour. The encounter with him is the decisive act of judgement. Before his gaze all falsehood melts away. This encounter with him, as it burns us, transforms and frees us, allowing us to become truly ourselves. All that we build during our lives can prove to be mere straw, pure bluster, and it collapses. Yet in the pain of this encounter, when the impurity and sickness of our lives become evident to us, there lies salvation. His gaze, the touch of his heart heals us through an undeniably painful transformation “as through fire”. But it is a blessed pain, in which the holy power of his love sears through us like a flame, enabling us to become totally ourselves and thus totally of God. In this way the inter-relation between justice and grace also becomes clear: the way we live our lives is not immaterial, but our defilement does not stain us for ever if we have at least continued to reach out towards Christ, towards truth and towards love. Indeed, it has already been burned away through Christ’s Passion.”
“In explanation of the Apostle’s words, they quoted the commentary of S. John Chrysostom, who, using the word fire, gives it the meaning of an eternal, and not temporary, purgatorial fire; explains the words wood, hay, stubble, in the sense of bad deeds, as food for the eternal fire; the word day, as meaning the day of the last judgment; and the words saved yet so as by fire, as meaning the preservation and continuance of the sinner’s existence while suffering punishment. Keeping to this explanation, they reject the other explanation given by S. Augustine, founded on the words shall be saved, which he understood in the sense of bliss, and consequently gave quite another meaning to all this quotation. “It is very right to suppose,” wrote the Orthodox teachers, “that the Greeks should understand Greek words better than foreigners. Consequently, if we cannot prove that any one of those saints, who spoke the Greek language, explains the Apostle’s words, written in Greek, in a sense different to that given by the blessed John, then surely we must agree with the majority of these Church celebrities.” The expressions sothenai, sozesthai, and soteria, used by heathen writers, mean in our language continuance, existence (diamenein, einai.) The very idea of the Apostle’s words shows this. As fire naturally destroys, whereas those who are doomed to eternal fire are not destroyed, the Apostle says that they continue in fire, preserving and continuing their existence, though at the same time they are being burned by fire. To prove the truth of such an explanation of these words by the Apostle, (ver. 11, 15,) they make the following remarks: The Apostle divides all that is built upon the proposed foundation into two parts, never even hinting of any third, middle part. By gold, silver, stones, he means virtues; by hay, wood, stubble, that which is contrary to virtue, i. e., bad works. “Your doctrine,” they continued to tell the Latins, “would perhaps have had some foundation if he (the Apostle) had divided bad works into two kinds, and bad said that one kind is purified by God, and the other worthy of eternal punishment. But he made no such division; simply naming the works entitling man to eternal bliss, i.e., virtues, and those meriting eternal punishment, i.e., sins. After which he says, ‘Every man’s work shall be made manifest,’ and shows when this will happen, pointing to that last day, when God will render unto all according to their merits: ‘For the day,’ he says, ‘shall declare it, because it shall be revealed by fire.’ Evidently, this is the day of the second coming of Christ, the coming age, the day so called in a particular sense, or as opposed to the present life, which is but night. This is the day when He will come in glory, and a fiery stream shall precede Him. (Dan. vii. 10; Ps. 1. 3; xcvii. 3; 2 S. Pet. iii. 12, 15.) All this shows us that S. Paul speaks here of the last day, and of the eternal fire prepared for sinners. ‘This fire,’ says he, ‘shall try every man’s work of what sort it is,’ enlightening some works, and burning others with the workers. But when the evil deed will be destroyed by fire, the evil doers will not be destroyed also, but will continue their existence in the fire, and suffer eternally. Whereas then the Apostle does not divide sins here into mortal and venial, but deeds in general into good and bad; whereas the time of this event is referred by him to the final day, as by the Apostle Peter also; whereas, again, he attributes to the fire the power of destroying all evil actions, but not the doers; it becomes evident that the Apostle Paul does not speak of purgatorial fire, which, even in your opinion, extends not over all evil actions, but over some of the minor sins. But these words also, ‘If any man’s work shall be burned, he shall suffer loss,’ (zemiothesetai, i.e., shall lose,) shows that the Apostle speaks of the eternal tortures; they are deprived of the Divine light: whereas this cannot be spoken of those purified, as you say; for they not only do not lose anything, but even acquire a great deal, by being freed from evil, and clothed in purity and candour.”” –The Greeks at the Council of Florence link: http://www.orthodoxinfo.com/death/stmark_purg.aspx