“I am speaking the truth in Christ—I am not lying; my conscience bears me witness in the Holy Spirit—” -Romans 9:1
What seems to be so much of an abrupt change in subject matter as to raise doubts in the minds of some scholars about the place of chapters 9-11 is not so dubious if we keep in mind the broader purpose of the letter and the circumstances surrounding the person writing it.
Paul is well known within the church and also to the Jews to have been a missionary to the Gentiles ( Galatians 2:8 Cf. Romans 11:13). Given the religious climate of the first century, this was no small indiscretion in the minds of the Sanhedrin as well as many Jewish believers.
Further, Paul has thus far spent a large portion of his letter showing how the Jews are just as guilty of sin as the Gentiles—they are sinners just the same in the eyes of God; there is no difference (Romans 2:12-29, 3:9-20). Given Paul’s ministry and now his articulation of the nature of the Jews’ sins, there would certainly be a need for some damage control (to speak in modern terms).
Here Paul begins with a strong oath, which in the Greek, begins with the word truth. He says,” Ἀλήθειαν λέγω ἐν Χριστῷ, οὐ ψεύδομαι (Truth I am telling in Christ; I’m not lying!).” This is striking given the final celebratory tone with which he concludes chapter 8. He continues the oath with a promise that the Holy Spirit is witness to his conscience about the truthfulness of what he is about to assert.
Paul will resume in chapter 12 his discussion of the implications of the gospel he has laid out in chapters 1-8. But before proceeding, Paul must digress for the sake of laying out the big picture of God’s historical-redemptive plan. And as shall be seen, redemption has all along been meant for Jews and Gentiles alike. As a matter of fact, the distinction is merely a temporary situation designed toward a particular end—the revelation of the Christ (Messiah)!