John Chrysostom

Now his meaning is this: If any man have an ill life with a right faith, his faith shall not shelter him from punishment, his work being burnt up. The phrase, "shall be burned up," means, "shall not endure the violence of the fire." But just as if a man having golden armor on were to pass through a river of fire, he comes from crossing it all the brighter; but if he were to pass through it with hay, so far from profiting, he destroys himself besides; so also is the case in regard of men's works. For he doth not say this as if he were discoursing of material things being burnt up, but with a view of making their fear more intense, and of shewing how naked of all defence he is who abides in wickedness. Wherefore he said, "He shall suffer loss:" lo, here is one punishment: "but he himself shall be saved, but so as by fire;" lo, again, here is a second. And his meaning is, "He himself shall not perish in the same way as his works, passing into nought, but he shall abide in the fire."

"He calleth it, however, "Salvation," you will say; why, that is the cause of his adding, "so as by fire:" since we also used to say, "It is preserved in the fire," when we speak of those substances which do not immediately burn up and become ashes. For do not at sound of the word fire imagine that those who are burning pass into annihilation. And though he call such punishment Salvation, be not astonished. For his custom is in things which have an ill sound to use fair expressions, and in good things the contrary. For example, the word "Captivity" seems to be the name of an evil thing, but Paul has applied it in a good sense, when he says, "Bringing into captivity every thought to the obedience of Christ." And again, to an evil thing he hath applied a good word, saying, "Sin reigned," here surely the term "reigning" is rather of auspicious sound. And so here in saying, "he shall be saved," he hath but darkly hinted at the intensity of the penalty: as if he had said, "But himself shall remain forever in punishment."