And after six days Jesus took with him Peter and James, and John his brother, and led them up a high mountain by themselves. And he was transfigured before them, and his face shone like the sun, and his clothes became white as light. (Matthew 17:1-2)
Here is another way that the mount of transfiguration is a parallel with the Church, for the Church is a city on a hill, a lamp on a stand, a people elevated that the glory of Christ might shine forth.
Of course Jesus has always had glory. He did not receive it at his transfiguration; he was always that majestic and awesome and glorious. It's just that his glory was not immediately visible. What happened on the mountain was an unveiling, a revelation, of the glory of the eternal Son; the glory he has had since before the creation of the world. [Jn 17:5]
Nor is it just to those first fortunate three that Christ's glory was revealed, for Paul writes:
And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit. (2Co 3:18)
Not only is Christ's glory unveiled to us, but through us (the Church), Christ's glory is unveiled to the world. Despite our imperfections, his perfect glory is reflected in us, and as we co-operate with the Spirit, that same glory is reproduced in us as we are transformed to be ever more like our Lord.
The Church is not just the place where God reveals his glory, but the people through whom he displays that glory to the world.
Out of Zion, the perfection of beauty, God shines forth. (Ps 50:2)
Jesus is already Lord of all, and the glory of God already fills the earth, but what us needed is a revelation of that glory, so the whole earth will be filled with the knowledge of the glory of God as the waters cover the sea.
The Church is God's prophetic demonstration to the world. In the church there is a revelation of the glory of God. In the church all bow the knee and confess Jesus as Lord. And so is declared the ultimate intention and destiny for all of God's earth.