19 You will say to me then, “Why does he still find fault? For who can resist his will?” 20 But who are you, O man, to answer back to God? Will what is molded say to its molder, “Why have you made me like this?” 21 Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use? 22 What if God, desiring to show his wrath and to make known his power, has endured with much patience vessels of wrath prepared for destruction, 23 in order to make known the riches of his glory for vessels of mercy, which he has prepared beforehand for glory— 24 even us whom he has called, not from the Jews only but also from the Gentiles?
Romans 9:19-24 ESV
Paul brings to mind this idea of a potter and his clay because the prophet Jeremiah once used this same metaphor for the Jewish people to help them see God’s sovereign work in Israel. Take a look at Jeremiah 18:1-6:
18 The word that came to Jeremiah from the Lord: 2 “Arise, and go down to the potter’s house, and there I will let you hear my words.” 3 So I went down to the potter’s house, and there he was working at his wheel. 4 And the vessel he was making of clay was spoiled in the potter’s hand, and he reworked it into another vessel, as it seemed good to the potter to do. 5 Then the word of the Lord came to me: 6 “O house of Israel, can I not do with you as this potter has done? declares the Lord. Behold, like the clay in the potter’s hand, so are you in my hand, O house of Israel.
God has already told Israel that He alone is the sovereign God, the Potter, and they are like clay in His hands. He may choose to do with them as He pleases. Because of original sin, all of us are like “spoiled clay,” God can decide to make us into whatever kind of vessel that seems good to Him. God will make some into vessels of wrath, which serve a purpose to Him, and He will make some into vessels of mercy, which will also serve a purpose to Him. He alone decides.