I like this passage to support purgatory, as does Cardinal Ratzinger (now Pope Benedict). From his book
Introduction to Christianity, he writes:
If [Purgatory] is understood in a properly Christian way when it is grasped christologically, in terms of the Lord himself as the judging fire which transforms us and conforms us to his own glorified body, then we shall come to a very different conclusion [than theologian Gnilka who denied a purgatorial interpretation of 1 Cor. 3:10-15]. Does not the real Christianizing of the early Jewish notion of a purging fire lie precisely in the insight that the purification involved does not happen through some thing, but through the transforming power of the Lord himself,
whose burning flame cuts free our closed-off heart, melting it, and pouring it into a new mold to make it fit for the living organism of his body?So you see how the transforming power is encounter with Christ himself, or as you said, grace itself. Also, Ratzinger refers to the “loss” of the closed-off heart. Our impurities are removed. The whole imagery of melting and pouring into a new mold is based on the language of the text. In 1 Corinthians 3, the precious metals are contrasted with wood/hay/straw - the things that burn up. This imagery is a reference to the ancient process of “smelting” in which precious metals were purified by fire of junk particles. You see references to this process in the Old Testament (eg. Ps 12:6, Is 48:10, Ez 22:22).
Getting back to Ratzinger:
The essential Christian understanding of Purgatory has now become clear. Purgatory is not, as Tertullian thought, some kind of supra-worldly concentration camp where man is forced to undergo punishment in a more or less arbitrary fasion. Rather* it is the inwardly necessary process of transformation in which a person becomes capable of Christ, capable of God and thus capable of unity with the whole communion of saints***.That help?