As NT Wright goes to great pains to show, Romans is about including both Jews and Gentiles in the one people of God. Paul urges the Romans, in 15:7, to welcome one another for, and here is a significant perspective of Paul:
Welcoming one another embodies the universal unity of the Church.
Christ, Paul says, become a servant of the circumcised in order to confirm the promises to the patriarchs about Gentile inclusion in the people of God (15:8-12). This leads Paul to show that the promises to the patriarchs can be found in 2 Sam 22:50; Ps 18:49 and Deut 32:43 and Ps 117:1 and Isa 11:10. Each of these texts reveals an inclusion of Gentiles. (By the way, Paul didn’t have a concordance as we do to find such texts — he had these texts in his head.)
And then to a “May the God of …” prayer: “May the God of hope fill you with all joy and peace in believing, so that you may abound in hope by the power of the Holy Spirit” (15:13).