John Calvin Commentary Isaiah 1:22

"Thy silver is become dross, thy wine mixed with water." — Isaiah 1:22 (ASV)

Thy silver is become dross, thy wine mixed with water. Isaiah speaks metaphorically and, by two comparisons, shows here that although the outward appearance of affairs was not openly overturned, their condition was changed and corrupted, making it widely different from what it had formerly been. For he says that dross now shines instead of gold, and that the wine, though it retains its color, has lost its flavor. “Though you still make an empty show,” says the Prophet, “yet nothing pure will be found in you; that wine which was accustomed to be pure in you is corrupted, and though its color deceives the eye, its taste shows that it has been mixed.”

All this means nothing more than that the Jews should lay aside hypocrisy, begin to confess their sins, and no longer flatter themselves as hypocrites do. The comparisons used here are excellently suited to this purpose. For dross bears some resemblance to gold, and similarly, the color of wine mixed with water resembles that of pure wine. Yet both are very far from having the purity of which they make an outward show. In the same way, hypocrites, by their hypocrisy, may be said to assume a false color of silver, though they are of no more value than dross. Indeed, they are all the more detestable because, although they are exceedingly wicked, they still present to God and men—with no less treachery than baseness—those hollow pretensions by which they cloak their malice.