James White writes/says of Romans 9:

So there is the context. Here is the cathedral of Christian revelation in Romans chapter 8 and as soon as he says this it becomes very, very clear that the apostle Paul knows that as soon as he makes these over arching statements of God’s victory in Christ and the elect in Christ and the perfection of the salvation that immediately on of the first objections that’s going to be raised is “But Paul, don’t you realize that if what you’re saying is true and we look around us and we see the vast majority of the Jewish people reject your message, they reject Jesus is the Messiah, does that not mean that God’s Word has failed?” And so in Romans chapter 9 we begin “I am telling the truth in Christ, I am not lying, my conscience testifies with. me in the Holy Spirit, that I have great sorrow and unceasing grief in my heart. For I could wish that I myself were accursed, {separated} from Christ for the sake of my brethren, my kinsmen according to the flesh, who are Israelites, to whom belongs the adoption as sons and the glory and the covenants and the giving of the Law and the {temple} service and the promises, whose are the fathers, and from whom is the Christ according to the flesh, who is over all, God blessed forever. Amen.” I prefer the NIV or New King James at that point. “Who is God over all blessed forever” I think it is in reference to the deity of Christ but we’re not going to spend our time on that.

Paul is writing to believers. Paul is not writing to atheists. In fact, Paul is writing to a hostile Christian audience. We see all sorts of accusations that Paul’s audience was making against him (e.g. Rom 3:8). White would have people believe that Paul’s audience’s primary question is about God’s word failing due to mass rejection by the Jews of Jesus. Paul was writing to Jews who accepted Jesus. Why on Earth would they think the promise had failed? Why would that be their starting assumption? They were living proof of God’s promise.

Instead, Paul has just detailed Gentile salvation! Paul’s Jewish audience would take that as rank heresy. Their primary thought at this point would be “Paul, you are saying that all God’s promises to Israel have failed. You are wrong.” Paul responds with Romans 9, describing why and how God can change His promises. Paul’s own conclusion of Romans 9 is a defense of his theme:

Rom 9:30 What shall we say then? That Gentiles, who did not pursue righteousness, have attained to righteousness, even the righteousness of faith;
Rom 9:31 but Israel, pursuing the law of righteousness, has not attained to the law of righteousness.
Rom 9:32 Why? Because they did not seek it by faith, but as it were, by the works of the law. For they stumbled at that stumbling stone.