Like I said in the previous post, of course “revealing” in itself does not mean “cleansing”. However, in the context of the allegory with the burning house both revealing and cleansing occur: the pure material is revealed because it is freed from the impurities, which burn out.
The Purgatory is not purging of sins. The blood of Jesus purges the sins. Someone in the Purgatory already has his sins forgiven, — or else he would be in Hell and not in Purgatory. This is expressed in the passage on hand by the fact that he is like a building on a solid foundation. He ends up saved. He is forgiven, but not yet perfect, like the building is on a solid foundation but has hay and stubble here and there. If he were burdened by sin he would be a different allegory: he would be like a building whose foundation is cracked or flooded.
So what are these things that burn? They are indeed false beliefs (to believe in something false is not always a sin), but also what in modern parlance is called “emotional baggage”: residual anger, despair, pride, — things the believer had confessed and has repented of, but that still are imperfections on his character. An analogy often used is this: let us say one has a tumor and he goes to a dcotor and the tumor is removed. That is confession and absolution of sin. Now, there remains a hole in his body. He is no longer sick of the tumor, but he is not healed either. He is imperfect. The Purgatory heals that scar.
On the fact that many Catholics don’t know their own faith — don’t get me started...
I guess we will just agree to disagree.