“How, sir,” I said, “did they become worse, after having known God?” “He that does not know God,” he answered, “and practices evil, receives a certain chastisement for his wickedness; but he that has known God, ought not any longer to do evil, but to do good. If, accordingly, when he ought to do good, he do evil, does not he appear to do greater evil than he who does not know God? For this reason, they who have not known God and do evil are condemned to death; but they who have known God, and have seen His mighty works, and still continue in evil, shall be chastised doubly, and shall die for ever. In this way, then, will the Church of God be purified. For as you saw the stones rejected from the tower, and delivered to the evil spirits, and cast out thence, so [they also shall be cast out, and] there shall be one body of the purified; as the tower also became, as it were, of one stone after its purification. In like manner also shall it be with the Church of God, after it has been purified, and has rejected the wicked, and the hypocrites, and the blasphemers, and the waverers, and those who commit wickedness of different kinds. After these have been cast away, the Church of God shall be one body, of one mind, of one understanding, of one faith, of one love. And then the Son of God will be exceeding glad, and shall rejoice over them, because He has received His people pure.” “All these things, sir,” I said, “are great and glorious.”
“Moreover, sir,” I said, “explain to me the power and the actions of each one of the mountains, that every soul, trusting in the Lord, and hearing it, may glorify His great, and marvellous, and glorious name.” “Hear,” he said, “the diversity of the mountains and of the twelve nations.”
Source: The Pastor (or "The Shepherd") (New Advent)