Psalm 40
The second half of Psalm 40 (Psalm 40:9–17) might be a good song to sing in response to your sermon. In these verses the psalmist commits himself to boldly proclaiming God’s truth, before acknowledging that he really needs God’s help and mercy to live in this world. Like the psalmist we want to be on our guard against false teachers, but due to our sinful natures we know we need God’s help to stop us from falling.
11 Woe to them! For they walked in the way of Cain and abandoned themselves for the sake of gain to Balaam’s error and perished in Korah’s rebellion.