ISB ~ 2 Corinthians 6 v1

in vain:Unless the Corinthians recognize and follow Paul as their apostolic father and founder, the “false apostles” (11:13) could lead them to spiritual ruin. The danger of falling from grace is a reality faced by every believer in this life (Gal 5:4; Heb 6:4-6; 2 Pet 2:20-22).