Matthew 17:6-8

This revelation had the same effect on Peter, James, and John that the revelation God gave the Israelites at Sinai did (Exodus 20:18-21; Deuteronomy 4:33; Hebrews 12:18-21) and that the revelation God gave Daniel had on him (cf. Daniel 10:8-12). When people see the glory of God revealed and realize that they are in His presence, they feel terror. The Transfiguration was mainly for the disciples’ benefit. Jesus brought the three disciples to the mountaintop, the Transfiguration happened before them, and the voice spoke to them. The disciples did not understand the significance of all they saw immediately. However, it was a revelation that God continued to help them understand, especially after the Resurrection (cf. 2 Peter 1:16-19). Immediately it did give them a deeper conviction that Jesus was the Messiah. [Note: See James A. Penner, "Revelation and Discipleship in Matthew’s Transfiguration Account," Bibliotheca Sacra 152:606 (April-June 1995):201-10.]

"The purpose of the transfiguration was primarily confirmation. It confirmed several vital facts. One of these was the reality of a future kingdom. The very fact that the transfiguration took place attests this. The presence of Old Testament saints on earth with Christ in a glorified state is the greatest possible verification of the kingdom promises in the Old Testament. The reality of this kingdom is also evident from the connection of the transfiguration with the promise of Matthew 16:27-28. The Son of Man was going to come one day to judge the world and establish His kingdom (Matthew 16:27). As an earnest of the coming of the kingdom three disciples were permitted to see the Son of Man in His kingdom (Matthew 16:28). This is exactly the manner in which Peter uses the transfiguration (2 Peter 1:16-21)." [Note: Toussaint, Behold the . . ., pp. 210-11. See also S. Lewis Johnson Jr., "The Transfiguration of Christ," Bibliotheca Sacra 124:494 (April-June 1967):133-43.]

Why did Jesus let only Peter, James, and John witness His transfiguration? Perhaps they were farther along in their faith than the other disciples. They were, after all, the core group of His disciples. Perhaps it was to avoid further misunderstanding among the disciples as a whole (cf. Matthew 17:9).