How do we know that Christ's ministry applies to both Jews and Gentiles?

In Romans 15:9-12, Paul cites Old Testament scriptures to demonstrate that the Gentiles would be included in God's redemptive plan, thus highlighting the universal scope of Christ's ministry. Prophets like Isaiah had foretold that the Messiah would reign over the Gentiles, reinforcing the idea that God's salvation is inclusive. Through Christ's resurrection and the command to His disciples to preach to all nations, we see the fulfilling of this promise, showing that Christ's ministry transcends ethnic and cultural boundaries.