As an apostle to the Gentiles, Paul was God’s instrument by which he ensured that the gospel went out to the nations. This vision is one that we also find in the Psalms (for example, Psalm 87; 47; 22). The concluding section of Psalm 22 might be especially appropriate to sing after your sermon.
11 For I would have you know, brothers, that the gospel that was preached by me is not man’s gospel.