Yes, the apostle Paul confirms the certainty of our salvation in Romans 10:9–13. The Gentile Christians in Rome confess that Jesus is their Lord, and they believe that God raised him up. The Gospel has come to them—it is in their mouth and in their heart. This is their salvation: If you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved
(Romans 10:9). To make sure they understand, Paul repeats it again (Romans 10:10): For with the heart one believes and is justified, and with the mouth one confesses and is saved.
Furthermore, he confirms the certainty of that salvation yet again with another word from Scripture: For the Scripture says, Everyone who believes in him will not be put to shame
(Romans 10:11). This last citation refers back to the one in Romans 9:33, where he repeated, in full, Isaiah’s prophecy (Isaiah 28:16) about the stumbling block that God will lay in Zion: As it is written, ‘Behold, I am laying in Zion a stone of stumbling, and a rock of offense; and whoever believes in him will not be put to shame.
Here he quotes only the last sentence for the purpose of confirming that people will be saved through faith in Jesus, the risen Lord.
The background of the letter to Rome was the situation in which the little Gentile-Christian church existed, namely in the capital city of the known world where many Jews also lived, is apparent from Romans 10:12–13. Although Paul had already said enough about salvation through faith in Christ in this letter, for the purpose of endowing his audience with even greater certainty he finds it necessary to expressly emphasize that this also applies to uncircumcised Gentile Christians: For there is no distinction between Jew and Greek; for the same Lord is Lord of all
(Romans 10:12a). For Paul this is not merely theoretical theology, but the reality of the Spirit. From Pentecost onwards, this reality can be experienced by all, for he bestows his riches on all who call on him. For everyone who calls on the name of the Lord will be saved
(Romans 10:12–13). Peter indeed used these very same words from Joel 2:32 thematically on the day of Pentecost in his sermon to all the Jews in Jerusalem. At the time Paul (Saul) rejected these words, but he has since learned to embrace them. The Spirit of holiness moves through all lands and testifies to the majesty of the risen Son of God (Romans 1:4). The readers of the letter, that is, the saints in Rome who were called, also belong to the people who now call upon the name of the Lord (Romans 1:6–7).1
9 because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.