John Gill emphasizes that the apostles did not follow cleverly devised fables but instead proclaimed the truth of Christ's power and coming based on their firsthand experiences and prophetic evidence. He contrasts the false teachings and myths prevalent in their time with the authentic witness of Christ's transfiguration, which affirmed His divine glory and future return. Gill highlights the significance of the apostles' eyewitness accounts as a foundation for their ministry, reinforcing the certainty of Christ's promises and the reality of His second coming.