Of Those Who Assert that All Catholics Who Continue in the Faith Even Though by the Depravity of Their Lives They Have Merited Hell Fire, Shall Be Saved on Account of the Foundation Of Their Faith
There are some, too, who found upon the expression of Scripture, “He that endures to the end shall be saved,” and who promise salvation only to those who continue in the Catholic Church; and though such persons have lived badly, yet, say they, they shall be saved as by fire through virtue of the foundation of which the apostle says, “For other foundation has no man laid than that which is laid, which is Christ Jesus. Now if any man build upon this foundation gold, silver, precious stones, wood, hay, stubble; every man's work shall be made manifest: for the day of the Lord shall declare it, for it shall be revealed by fire; and each man's work shall be proved of what sort it is.
If any man's work shall endure which he has built thereupon, he shall receive a reward. But if any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as through fire.” They say, accordingly, that the Catholic Christian, no matter what his life be, has Christ as his foundation, while this foundation is not possessed by any heresy which is separated from the unity of His body. And therefore, through virtue of this foundation, even though the Catholic Christian by the inconsistency of his life has been as one building up wood, hay, stubble, upon it, they believe that he shall be saved by fire, in other words, that he shall be delivered after tasting the pain of that fire to which the wicked shall be condemned at the last judgment.
Source: City of God (New Advent)