Paul is amazed that God has called him to bring the message of Jesus to Gentiles. Having been raised as a Jew, he didn’t see this coming. For him, there was always a strict line of division between Jews and Gentiles. Now he gets the chance to introduce everyone to Jesus regardless of their heritage. He prays his readers will grow stronger in their faith.
We have the same privilege as Paul. We can take the message of Jesus to anyone; the worst of sinners, the poorest of people, those we don’t like, and those who seem least likely to listen.