What does Matthew 17:2 mean?
This simple sentence describes one of the most amazing events in the lives of Peter, James, and John. This moment confirmed in dazzling light what they already believed to be true: Their master Jesus was the Son of the God of heaven. The word "transfigured" comes from the Greek word metamorphoō. This is the root word for English terms like metamorphosis and is translated as "transformed" in verses like 2 Corinthians 3:18.This moment connects Jesus to both Moses and Elijah, who appear in the following verses. Moses' face also shone brightly after He spent time with God (Exodus 34:29–30), but that shining was only the reflection of God's glory. Jesus is transformed from the inside out into His glorious appearance in heaven before coming to earth. Peter, James, and John are witnessing Jesus in a state more representative of His nature as the Son of God.
The two words that characterize Jesus' transfigured appearance are "light" and "white." His face shines like the sun, and His clothes are as white a light. Mark's account describes Jesus' clothes as more intensely white than anyone on earth could bleach them (Mark 9:3). Jesus literally becomes a source of light before their eyes.
The disciples are witnessing nothing less than the glory of God in the person of Jesus. It is a moment that will stick with them forever, confirming to them Jesus' identity as God's Son. John will begin His own gospel affirming the fact that "we have seen his glory, glory as of the only Son from the Father" (John 1:14). Peter will also testify about it in one of his letters: "We were eyewitnesses of his majesty. For when he received honor and glory from God the Father, and the voice was borne to him by the Majestic Glory, 'This is my beloved Son, with whom I am well pleased,' we ourselves heard this very voice borne from heaven, for we were with him on the holy mountain" (2 Peter 1:16–18).