Paul just got through declaring God's Sovereign control of man with "He has mercy on whom He desires, and He hardens whom He desires" (Romans 9:18).
You are deathly wrong.
It is written that no purpose of God's can be thwarted (Job 42:2), so scripture reveals that man cannot resist God's will, and Paul knows scripture.
You do not know scripture.
Your "free will" is not mentioned in the passage, in fact, the Apostle Paul leaves no room for dispute in a person who believes God.
Immediately after writing that God is in control Paul continued with "You will say to me then, 'Why does He still find fault? For who resists His will?'” (Romans 9:19)
Romans 9:18 segues right into Romans 9:19-23.
Bringing these together:
Paul conveyed "God is in control" (Romans 9:18) then the "you" defiantly mocks God's control with "You realize in your theology if people don't believe the scripture it's because God doesn't allow them to, right?" like in Romans 9:19, because your words align so well with the actual Romans 9:19 content).
The "you" in Romans 9:19-20 is the person who rejects God by way of rejecting God's exclusive control of man's salvation; in other words, the "you" is the person that claims man controls man (what you call "free will"), yet Paul explains God controls man.
Do not forget that it is written that no purpose of God's can be thwarted (Job 42:2), so scripture reveals that man cannot resist God's will, and Paul knows scripture.
Notice the "you" questioning why God still finds fault. Paul conveys that the "you" asks the fault question in a mocking manner, and the subsequent question about God's will continues with the "you" mocking the One True God who is entirely in control of man's salvation according to Paul (Ephesians 2:8-10 for example).
The "you" mocking is certain because immediately after the question about God's will, Paul wrote:
On the contrary, who are you, O man, who answers back to God? The thing molded will not say to the molder, “Why did you make me like this,” will it? (Romans 9:20)
See the "On the contrary" which is indicative that the following statement of Paul refutes the mocking questions of the "you" about fault and about God's will (in Romans 9:19).
Regardless of "Who is Paul’s hypothetical objector", Paul continues immediately after "On the contrary" in Romans 9:20 showing that the thing molded cannot resist the will of the Molder.
The thing molded represents the "you".
The Molder represents God.
IN TRUTH, PAUL CONVEYS THAT MAN CANNOT RESIST GOD'S WILL (ROMANS 9:19-20)!
The Truth (John 14:6) is that Lord Jesus Christ died exclusively to save all the vessels of mercy, which He prepared beforehand for glory.
True, man's will is not free, it is bound. Christ tells us He is the one who makes a man free, not the devil who has blinded the minds of unbelievers, as 2 Corinthians 4 says. If they are blinded in their minds they can not believe. a clear example of how people just dont change are the many disputers of the scripture.
Therefore, since we have this ministry, as we have received mercy, we do not lose heart. 2 But we have renounced the hidden things of shame, not walking in craftiness nor handling the word of God deceitfully, but by manifestation of the truth commending ourselves to every man’s conscience in the sight of God.
3 But even if our gospel is veiled, it is veiled to those who are perishing, 4 whose minds the god of this age has blinded, who do not believe, lest the light of the gospel of the glory of Christ, who is the image of God, should shine on them. 5 For we do not preach ourselves, but Christ Jesus the Lord, and ourselves your bondservants for Jesus’ sake. 6 For it is the God who commanded light to shine out of darkness, who has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.
Here is a perfect example of how messed up people try to prove God is the Father of ALL, but the context here is the church only.
Ephesians 4, teaching about unity among believers only, we are not united with the WORLD which is perishing, who do not believe whose minds are blinded to the gospel of Christ by the devil, who is their spiritual father. I have had so many conversations with people who try to use scripture to say God is the Father of all.
Ephesians 4
I, therefore, the prisoner of the Lord, beseech you to walk worthy of the calling with which you were called, 2 with all lowliness and gentleness, with longsuffering, bearing with one another in love, 3 endeavoring to keep the unity of the Spirit in the bond of peace. 4
There is one body and one Spirit, just as you were called in one hope of your calling; 5
one Lord, one faith, one baptism; 6 one God and Father of all, who is above all, and through all, and in you all.
Clearly, the people of the world are not the people of God, The same Paul the apostle wrote both of these books.
The New Man
17 This I say, therefore, and testify in the Lord, that you should no longer walk as the rest of the Gentiles walk, in the futility of their mind, 18 having their understanding darkened, being alienated from the life of God, because of the ignorance that is in them, because of the blindness of their heart; 19 who, being past feeling, have given themselves over to lewdness, to work all uncleanness with greediness.
20 But you have not so learned Christ, 21 if indeed you have heard Him and have been taught by Him, as the truth is in Jesus: 22 that you put off, concerning your former conduct, the old man which grows corrupt according to the deceitful lusts, 23 and be renewed in the spirit of your mind, 24 and that you put on the new man which was created according to God, in true righteousness and holiness.
The OLD man, can not be saved, only the NEW man of the Spirit is saved.
All unbelievers are the OLD man, and they walk as the unbelieving gentiles walk, according to the prince of the power of the air (the devil).
It is why we must be born again before we will believe in our heart that God raised Christ from the dead, and confess Christ as Lord and be saved. God must make us alive who were dead, and that is the gift of God lest anyone should boast that they chose God. The old nature, is the carnal mind and we also read about that in Romans 8
5 For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit, the things of the Spirit. 6 For to be carnally minded is death, but to be spiritually minded is life and peace. 7
Because the carnal mind is enmity against God; for it is not subject to the law of God, nor indeed can be. 8 So then, those who are in the flesh cannot please God.
9 But you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. Now if anyone does not have the Spirit of Christ, he is not His. 10 And if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness. 11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies [d]through His Spirit who dwells in you.