Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Jer 18:1-10) God's power over his creatures is represented by the potter.
(Jer 18:11-17) The Jews exhorted to repentance, and judgments foretold.
(Jer 18:18-23) The prophet appeals to God.
While Jeremiah looks upon the potter's work, God darts into his mind two great truths. God has authority, and power, to form and fashion kingdoms and nations as he pleases. He may dispose of us as he thinks fit; and it would be as absurd for us to dispute this, as for the clay to quarrel with the potter. But he always goes by fixed rules of justice and goodness. When God is coming against us in judgments, we may be sure it is for our sins; but sincere conversion from the evil of sin will prevent the evil of punishment, as to persons, and to families, and nations.
Sinners call it liberty to live at large; whereas for a man to be a slave to his lusts, is the very worst slavery. They forsook God for idols. When men are parched with heat, and meet with cooling, refreshing streams, they use them. In these things men will not leave a certainty for an uncertainty; but Israel left the ancient paths appointed by the Divine law. They walked not in the highway, in which they might travel safely, but in a way in which they must stumble: such was the way of idolatry, and such is the way of iniquity. This made their land desolate, and themselves miserable. Calamities may be borne, if God smile upon us when under them; but if he is displeased, and refuses his help, we are undone. Multitudes forget the Lord and his Christ, and wander from the ancient paths, to walk in ways of their own devising. But what will they do in the day of judgment!
When the prophet called to repentance, instead of obeying the call, the people devised devices against him. Thus do sinners deal with the great Intercessor, crucifying him afresh, and speaking against him on earth, while his blood is speaking for them in heaven. But the prophet had done his duty to them; and the same will be our rejoicing in a day of evil.