This is a message from God to Israel. A people in a covenant relationship with God.
God mentions about Gentile nations their certain destruction if they do not repent to teach Israel that if they do not repent, He will also destroy them.
Israel would have known and understood and seen with their eyes what happened to the ungodly gentile nations. God is telling Israel neither will they escape disaster unless they repent. They will have the same fate. God the potter does with them what He wishes, they are in His hands for judgement. Their sins are their undoing, not God. Same today. People die in their sins, because they are sinners. God can do whatever He wants with them, so they are the clay and He the potter.
Jeremiah 18New King James Version (NKJV)
The Potter and the Clay
18 The word which came to Jeremiah from the Lord, saying: 2 “Arise and go down to the potter’s house, and there I will cause you to hear My words.” 3 Then I went down to the potter’s house, and there he was, making something at the wheel. 4 And the vessel that he made of clay was marred in the hand of the potter; so he made it again into another vessel, as it seemed good to the potter to make.
5 Then the word of the Lord came to me, saying: 6 “O house of Israel, can I not do with you as this potter?” says the Lord. “Look, as the clay is in the potter’s hand, so are you in My hand, O house of Israel!
7 The instant I speak concerning a nation and concerning a kingdom, to pluck up, to pull down, and to destroy it, 8 if that nation against whom I have spoken turns from its evil, I will relent of the disaster that I thought to bring upon it. 9 And the instant I speak concerning a nation and concerning a kingdom, to build and to plant it,10 if it does evil in My sight so that it does not obey My voice, then I will relent concerning the good with which I said I would benefit it.
11 “Now therefore, speak to the men of Judah and to the inhabitants of Jerusalem, saying, ‘Thus says the Lord: “Behold, I am fashioning a disaster and devising a plan against you. Return now every one from his evil way, and make your ways and your doings good.”’”