What did Peter, James, and John see on the Mount of Transfiguration?
Peter, James, and John saw Jesus Christ literally glorified in their presence. He took on such glory that even His clothing radiated the very glory of heaven. This visible manifestation provided a picture of Christ's glory and confirms that believers, though unseen by others, are seen as glorified by God.
In the context, the Mount of Transfiguration is used as an illustration of the believer's glorification. Les explains that Peter, James, and John had the opportunity to see Christ literally glorified, and He took on such glory that even His clothing radiated the very glory of heaven. Just as God says believers are already glorified, fellow man does not see a halo or an angelic presence, but God does. When God looks upon the believer, He does not see that person in particular; He sees Christ Jesus. Since God says believers are justified and glorified, He views them as glorified when He looks on them.