In Isaiah one, verse twenty-five, “And I will turn my hand upon thee, and purely purge away thy dross, and take away all thy tin.” God intended to purge away evil from His people and to restore a remnant who repented, as in verses eighteen to nineteen, twenty-six through twenty-seven. He was not finished yet with Judah, as in verses fourteen through sixteen. Still, the redeemer of the entire human race had to come through these chosen people. Although “Zion” in verse twenty-seven would be restored, only those who truly turned to God would be saved and not destroyed, as in Isaiah sixty-five, verses eight to sixteen.
Neither holy cities nor royal ones are faithful to their trust if the Son of God does not dwell in them. Dross may shine like silver, and the wine that is mixed with water may still have the colour of wine. Those have a great deal to answer for, who do not help the oppressed, but oppress them. Men may do much by outward restraint, but only God works effectually by the influences of His Spirit, as a Spirit of Judgment. Sin is the worst captivity, the worst slavery. The redemption of the spiritual Zion, by the righteousness and death of Christ, and by His powerful grace, most fully accord with what is here meant. Utter ruin is threatened.
Dross is not the sins but the sinful persons that would cause or tempt the people of God to sin, such as enemies. Today, many believers have individuals around them that attempt to cause trouble that the devil uses to get under their skin, provoking them to anger, so they cannot connect wth God. The best thing to do for believers is ask God how to handle the situation.