Romans 9 is rich with “proof text” for Calvinism:
Romans 9:20-24 “Nay but, O man, who art thou that repliest against God? Shall the thing formed say to him that formed it, Why hast thou made me thus? Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour? What if God, willing to shew his wrath, and to make his power known, endured with much longsuffering the vessels of wrath fitted to destruction: And that he might make known the riches of his glory on the vessels of mercy, which he had afore prepared unto glory, Even us, whom he hath called, not of the Jews only, but also of the Gentiles?”
It seems right here that the vessels were fit for wrath and mercy, and the vessels cannot say to God “Why did you make me thus?”
To know whether a vessel is made for honor and dishonor is to see whether they serve God. There’s always a “condition” involved, that is the one pivotal argument we need to use in every Calvinist verse. c.f
Jeremiah 18:4-10 “And the vessel that he made of clay was marred in the hand of the potter: so he made it again another vessel, as seemed good to the potter to make it. Then the word of the LORD came to me, saying, O house of Israel, cannot I do with you as this potter? saith the LORD. Behold, as the clay is in the potter’s hand, so are ye in mine hand, O house of Israel. At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it; If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do unto them. And at what instant I shall speak concerning a nation, and concerning a kingdom, to build and to plant it; If it do evil in my sight, that it obey not my voice, then I will repent of the good, wherewith I said I would benefit them.”
v8 notice that the potter says ‘I can make you a vessel fit for wrath’ but when the vessel follows a condition here (turn away from evil and serve God), then God will repent and change His mind.
v10 He can also make the vessel who is fit for mercy and blessing for wrath if it does not follow a certain condition.
Jeremiah 19:4 “Because they have forsaken me, and have estranged this place, and have burned incense in it unto other gods, whom neither they nor their fathers have known, nor the kings of Judah, and have filled this place with the blood of innocents;”
Jeremiah 19:11 “And shalt say unto them, Thus saith the LORD of hosts; Even so will I break this people and this city, as one breaketh a potter’s vessel, that cannot be made whole again: and they shall bury them in Tophet, till there be no place to bury.”
Notice in v11, because they did those things (forsaken God, worshipped idols) in v4, their free choice of rebelling against God, God made them a vessel fit for wrath.
2 Timothy 2:20-23 “But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour. If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master’s use, and prepared unto every good work. Flee also youthful lusts: but follow righteousness, faith, charity, peace, with them that call on the Lord out of a pure heart. But foolish and unlearned questions avoid, knowing that they do gender strifes.”
There are vessels that are honorable and dishonorable based on a condition. In v21, notice that God didn’t make them do it, it’s their free will. v22 is telling us to follow that free choice so that we can be a vessel that’s honorable. Why would it tell us to do the action if God’s supposed to control the person?
Romans 9:15-16 “For he saith to Moses, I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion. So then it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy.”
Romans 9:18-19 “Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth. Thou wilt say then unto me, Why doth he yet find fault? For who hath resisted his will?”
v16 is a Calvinist’s favorite line that we cannot put freewill there. v19 is where Calvinist claims that no one can resist God’s will, so there’s no free will involved.
The point is that it is true that God has the right to choose whoever to have mercy or reprobation. He chooses those who are saved and serve Him to receive mercy and if we’re not saved then He chooses us to be a reprobate in His eyes. That is God’s will and mankind’s will cannot undo it.
If we’re saved and we serve God, then no matter what, our will cannot change what God wills and ordains: we’re going to heaven, and we’re a finer vessel than before.
If we’re lost, we’re a vessel fit for wrath and no matter what we say, we can’t change God’s will on that. If we want to rebel and do wicked things, we’re going to be a dishonorable vessel. No shortcut, no loophole, no other scriptures to justify our sins.
Remember the verse that mentioned that God can show mercy to whom He will have mercy and whoever He wants to harden, He will harden. This is always based on a condition.
Exodus 20:5-6 “Thou shalt not bow down thyself to them, nor serve them: for I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me; And shewing mercy unto thousands of them that love me, and keep my commandments.”
God is commanding them to do this action, they have to do it themselves, He can’t make them. v6 He can show mercy based on the condition that they love God and keep His commandments.
It’s always based on a condition and God will ordain which one as a result consequently, a vessel fitted for wrath and a vessel fitted for mercy.