John Wesley addresses the issue of peer pressure through the example of Peter's actions in Antioch, where Peter initially associates with Gentiles but withdraws due to fear of the circumcision group. This hypocrisy not only affects Peter but also leads others, including Barnabas, astray. Wesley emphasizes the importance of maintaining purity of heart and the courage to stand firm in faith, even in the face of potential persecution. He highlights that the desire to please God must outweigh the desire to conform to societal pressures. The sermon encourages believers to seek strength from the Holy Spirit to resist peer pressure and uphold their convictions.