Jerome : (Verse 17) They have turned back: let them be confounded with confusion, that trust in idols, that say to molten things: You are our gods. LXX: but they have turned backward; you will be confused with confusion, you who trust in idols, who say that they are gods. But when this was said, the Jewish people turned backward so as not to believe the promise, and in their errors they were confused and neglected the pledge of God, whom they had believed in before idols. Or when the fullness of the Gentiles has come in, then also the people of Israel will be converted (Rom. II), and they will repent of their error, by which they had served idols before. Or certainly after the calling of the Gentiles, they will return to the beginning: so that it may be said, all the Gentiles who did not want to believe in the Gospel will be confounded in their idols. — Commentary on Isaiah