4For certain people have crept in unnoticed who long ago were designated for this condemnation, ungodly people, who pervert the grace of our God into sensuality and deny our only Master and Lord, Jesus Christ.
Psalm 34
The second half of Psalm 34 (Psalm 34:11–22), explains what it means to fear the Lord, what it means to live in relationship with God in response to his grace. This would be a good song to sing at the conclusion of your sermon.
4 For certain people have crept in unnoticed who long ago were designated for this condemnation, ungodly people, who pervert the grace of our God into sensuality and deny our only Master and Lord, Jesus Christ.