J. R. R. Tolkien explains our fantastical writing (i.e. the writing of fantasy literature) flows from and because of Whose image we bear,
We make in our measure and in our derivative mode, because we are made: and not only made, but made in the image and likeness of a Maker.”
C. S. Lewis furthers the point and relaying it specifically to Christ:
Now as myth transcends thought, Incarnation transcends myth. The heart of Christianity is a myth which is also a fact. The old myth of the Dying God, without ceasing to be myth comes down from the heaven of legend and imagination to the earth of history. It happens-at a particular date, in a particular place, followed by definable historical consequences. We pass from a Balder or an Osiris, dying nobody knows when or where, to a historical Person crucified (it is all in order) under Pontius Pilate. By becoming fact it does not cease to be myth: that is the miracle. – C.S. Lewis, God in the Dock: Essays on Theology and Ethics, “Myth Became Fact”
The peculiar quality of the ‘joy’ in successful Fantasy can thus be explained as a sudden glimpse of the underlying reality or truth. It is not only a ‘consolation’ for the sorrow of this world, but a satisfaction, and an answer to that question, ‘Is it true?’ . . . In the ‘eucatastrophe’ we see in brief vision that the answer may be greater–it may be a far-off gleam or echo of evangelium in the real world . . . The Gospels contain a fairy-story, or a story of a larger kind which embraces all the essence of fairy-stories. They contain many marvels–peculiarly artistic, beautiful, and moving: ‘mythical’ in their perfect, self-contained significance; and among the marvels is the greatest and most complete conceivable eucatastrophe. But this story [i.e. the Christian Story] has entered History and the primary world; the desire and aspiration of sub-creation [those who write and enjoy fanatasy literature] has been raised to the fulfillment of Creation. The Birth of Christ is the eucatastrophe of Man’s history. The Resurrection is the eucatastrophe of the story of the Incarnation. This story begins and ends in joy. It has pre-eminently the ‘inner consistency of reality’. There is no tale ever told that men would rather find was true. ~J.R.R. Tolkien
In Letter 89 by Tolkien to Christopher Tolkien (pp. 99-100):
…I coined the word ‘eucatastrophe’: the sudden happy turn in a story which pierces you with a joy that brings tears (which I argued it is the highest function of fairy stories to produce). And I was there led to the view that it produces its peculiar effect because it is a sudden glimpse of truth…. It percieves– if the story has literary ‘truth’…–that this is indeed how things really do work in the Great World for which our nature is made. And I concluded by saying that the Resurrection was the greatest ‘eucatastrophe’ possible in the greatest fairy story– and produces that essential emotion: Christian joy which produces tears because it is qualitatively so like sorrow, because it comes from those places where Joy and Sorrow are at one, reconciled, as selfishness and altruism are lost in Love…
So it may be said that the chief purpose of life, for any one of us, is to increase according to our capacity our knowledge of God by all the means we have, and to be moved by it to praise and thanks. ~J.R.R. Tolkien in a letter to Camilla Unwin – May 20, 1969