The transfiguration unveiled the nature of Christ's kingdom glory. In an age of unbelief we must act on our faith in the victory of Christ over all things.
Like the Pharisees Peter saw the issue of Christ's identity in man-centred terms. To follow Jesus means to deny our own interests and to prioritize His interests.
The focus of Scripture is the redemption of all of life in the person of Jesus. The miracles related in the gospels are designed to advance the redemptive story.