In Isaiah, we begin the oracles against the nations. These type of judgment oracles are typical of the prophecy genre. They show that God is sovereign, not just over Israel, but over the Gentile nations as well.
In Romans, Paul stresses again that God’s plan for salvation has always included the Gentiles.
For I tell you that Christ became a servant to the circumcised to show God’s truthfulness, in order to confirm the promises given to the patriarchs, and in order that the Gentiles might glorify God for his mercy (Romans 15:8).
That’s a mouthful, but oh, the riches contained in that verse!! Christ’s life, death and resurrection proved that God’s word was true. Every Old Testament promise was fulfilled in Christ. And because of Jesus, the way has been opened for all to receive his mercy and enter the Kingdom of God!!
Isaiah’s judgment oracles should remind us to run away from God’s judgment by running into His kindness… Let the truth of the gospel sink into your heart and cause you to wonder at the awesome power and goodness of our God!!