Now then, with the text of Romans 9, Paul starts by saying that he would rather be damned if it meant his people would be saved. This is soteriology. Not only will Paul continue using the soteriological terminology he has used in the other chapters (as 9-11 is built on the foundation of 1-8), but the whole intent of his discourse is to answer the question of why the Jews apostatized and the Gentiles converted? This is his point in verses 6-13. Certainly he would have no argument without it, but it is the foundation for his actual argument, not the argument itself. Paul's point is that the Jews were not the people of God, the Church was, and Israel was simply the only Christian nation under the old covenant. God is not breaking His promise because His promise was to His covenant people. Now I found this line really telling
Is being the covenanted people of God merely a temporal blessing? Is having the promise of unending grace and mercy merely a temporal blessing? Is having the very Son of God die for you merely a temporal blessing? I should certainly hope not, since then we of all people are most to be pitied.
The argument that verse 11 is about what means God will use and not salvation is preposterous, considering the verse uses the words election, call and work, each of which already has an established soteriological meaning in the epistle, especially in the immediately preceding chapter. This interpretation requires us to isolate the passage as though it were a different book (indeed, a different author, since the meaning of these words is consistent throughout Paul). Now before I address his dealing with verses 14-18 I feel I must deal with what I have thus far left untouched. Central to this person's argument is that Paul is arguing against the judaizers. This was concluded in Romans 8, now Paul is working out the implications of all this as regards the people of Israel. Paul is dealing with nations, yes, but the question of why some are covenanted and why some are apostate. Are we to suppose that mercy has nothing to do with salvation? Does being hardened against Christ have nothing to do with salvation? I wonder what salvation is with such a perspective.
The leap all the way back to Romans 3 annihilates the context and flow of the passage so we will take no notice of it. Regarding the objection, we must ask the question, is this not the very objection raised most against the doctrines of grace? Do we not see synergist after synergist argue that God is unjust to damn sinners if He is sovereign? That is why this is an objection, not because of God using our sins, but of God determining our ends. The objection is that it isn't their fault that they were so wicked (in this case, unbelieving) because they were so due to God's eternal decree. That is why Paul's mocking hypothesis of a pot asking a potter "why have you made me like this" is raised. Did the pot make itself dishonorable, and then the potter use that for something? Or did the potter make it for dishonorable use for his own purposes? Paul's point in utilizing the motif is to show that the creator has a right to determine the purpose of His own creation, even if that purpose is to be destroyed "that I might show my power in you". He is wrong when he says the clay is Israel. The clay is obviously creatures. The reference to 2 Timothy 2 is totally fallacious, since the contexts are completely different; there is nothing about God as creator, nothing about Israel, nothing about election, nothing about mercy, nothing about hardening, the analogy is about cleansing oneself from false brothers in the church.
I can think of few things more directly contrary to Romans 9:16-21. Rather than it not being depended on "human will or exertion" but He "who has mercy", making "out of the same lump one vessel for honorable use and another for dishonorable use", it is dependent entirely on human will, not on He who has mercy, even acting in defiance of the use for which He made them. I suppose the clay does say to the potter "What are you making?" or "Your work has no handles".
I think this is a good place to conclude and say that this person has failed to establish their claim, and that the passage shows the sovereignty of God over salvation, who has mercy on whom He will have mercy, and hardens those whom He will harden.