“I am speaking the truth in Christ—I am not lying; my conscience bears me witness in the Holy Spirit— that I have great sorrow and unceasing anguish in my heart. For I could wish that I myself were accursed and cut off from Christ for the sake of my brothers, my kinsmen according to the flesh.” -Romans 9:1–3
Paul wants it to be clear to his readers that in no uncertain terms is he merely a disinterested bystander regarding the plight of the Jews—their rejection of their Messiah.
He has great sorrow and unceasing anguish in his heart because of their condition. That the language here is superfluously pathetic in the rhetorical sense does not diminish its reality. It’s not like a child waiting for his breakfast who cries to his mother, I’m starving! But it’s much closer to someone who hasn’t eaten for a couple of days moaning, I’m literally starving! Paul is expressing in the strongest language possible just how distressed he is over their impending judgment and condemnation.
To demonstrate to what degree he is broken hearted, he announces that he could wish he could change places with them if it would help them be saved. Could wish is the translation of ηὐχόμην, an imperfect, middle/passive verb meaning he contemplates the idea that if it were possible to do so). In other words, Paul is not changing his theology or wishing something that could not actually be the cases. Rather, he is continuing to express in the strongest possible terms just how deeply anxious he is over the plight of the unbelieving Jews.
In other words, Paul wants the church at Rome to know, he’s not against the Jews. He’s the kind of man who is so deeply burdened by their need for salvation, he is willing to risk everything for their conversion, even the damnation of his own soul if such a thing were possible that they might be redeemed.