reveling in their deception as they feast with you: Compare Jude 1:12. Early Christians often shared fellowship meals to honor the Lord (see Acts 2:46; 6:1). The false teachers used these meals as opportunities to deceive true believers.
Some manuscripts say They revel in their fellowship meals as they feast with you. If correct, these false teachers were using the meals for self-indulgence (see 1 Corinthians 11:20–22).