Matthew Henry Commentary Isaiah 1:21-31

"How is the faithful city become a harlot! she that was full of justice! righteousness lodged in her, but now murderers. Thy silver is become dross, thy wine mixed with water. Thy princes are rebellious, and companions of thieves; every one loveth bribes, and followeth after rewards: they judge not the fatherless, neither doth the cause of the widow come unto them. Therefore saith the Lord, Jehovah of hosts, the Mighty One of Israel, Ah, I will ease me of mine adversaries, and avenge me of mine enemies; and I will turn my hand upon thee, and thoroughly purge away thy dross, and will take away all thy tin; and I will restore thy judges as at the first, and thy counsellors as at the beginning: afterward thou shalt be called The city of righteousness, a faithful town. Zion shall be redeemed with justice, and her converts with righteousness. But the destruction of transgressors and sinners shall be together, and they that forsake Jehovah shall be consumed. For they shall be ashamed of the oaks which ye have desired, and ye shall be confounded for the gardens that ye have chosen. For ye shall be as an oak whose leaf fadeth, and as a garden that hath no water. And the strong shall be as tow, and his work as a spark; and they shall both burn together, and none shall quench them." — Isaiah 1:21-31 (ASV)

Neither holy cities nor royal ones are faithful to their trust if religion does not dwell in them. Dross may shine like silver, and 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.

People may do much by outward restraints; but only God works effectively 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 accords with what is meant here.

Utter ruin is threatened. The Jews would become like a tree blasted by heat or like a garden without water, which in those hot countries would soon be burned up. Thus will those be who trust in idols or in an arm of flesh. Even the strong man will become like tow—not only quickly broken and pulled to pieces, but easily catching fire.

When the sinner has made himself like tow and stubble, and God makes Himself like a consuming fire, what can prevent the utter ruin of the sinner?