The dark background against which Jesus is shown [in the transfiguration icon] is something you will see in other icons as a way of representing the depths of heavenly reality. In the transﬁguration, what the disciples see is, as you might say, Jesus’ humanity “opening up” to its inner dimensions. …So the disciples look at Jesus, and see him as coming out from an immeasurable depth; behind or within him, inﬁnity opens up, “the dwelling of the light”, to borrow the haunting phrase from Job 38.19.
…Second, there is the connection of the [transfiguration] icon …and the story with the end of Jesus’ earthly life. God can live in the middle of death. That is good news on one level; on another, it means that living with God will not spare us trial, agony and death. In the Gospels, when Jesus has received Peter’s admission of faith – “You are the Anointed, the Son of the Living God” — he immediately goes on to predict his betrayal and death, and Peter protests. It is as if, there as here [in the icon], [Peter] lifts his hand to his eyes because he can’t manage what he sees. If only the vision of glory spared us suffering! But on the contrary, glory can only be seen for what it really is when we see it containing and surviving disaster.
…The Orthodox hymns for the feast of the Transﬁguration make the point often made by Orthodox theologians: Peter, James and John are allowed to see Christ’s glory so that when they witness his anguish and death they may know that these terrible moments are freely embraced by the God-made-human who is Jesus, and held within the inﬁnite depth of life. It is surely not an accident that it is Peter and James and John who are also with Jesus in Gethsemane: the extreme mental and spiritual agony that appears there is the test of what has been seen in the transﬁguration. We are shown that God can be God even in the very heart of human terror: the life of Jesus is still carried along by the tidal wave of that which the dark background of glowing blues and reds in the icon depicts, the life of God.
…This is the great challenge to faith: knowing that Christ is in the heart of darkness, we are called to go there with him. In John 11, Thomas says to the other disciples, “Let us go and die with him”; and ahead indeed lies death — the dead Lazarus decaying in the tomb, the death of Jesus in abandonment, your death and mine and the deaths of countless human beings in varying kinds of dark night. But if we have seen his glory on the mountain, we know at least, whatever our terrors, that death cannot decide the boundaries of God’s life. With him the door is always open, and no one can shut it.The Dwelling of the Light: Praying with Icons of Christ by Rowan Williams.