The Grand Miracle: by CS Lewis (from Miracles)

Isaiah 7:14
 Therefore the Lord himself will give you a sign: The virgin will be with child and will give birth to a son, and will call him Immanuel.
Matthew 1:23
 "The virgin will be with child and will give birth to a son, and they will call him Immanuel"--which means, "God with us."

The central miracle asserted by Christians is the Incarnation. They say that God became Man. Every other miracle prepares for this, or exhibits this, or results from this. Just as every natural event is the manifestation at a particular place and moment of Nature's total character, so every particular Christian miracle manifests at a particular place and moment the character and significance of the Incarnation. There is no question in Christianity of arbitrary interferences just scattered about. It relates not a series of disconnected raids on Nature but the various steps of a strategically coherent invasion—an invasion which intends complete conquest and 'occupation'. The fitness, and therefore credibility, of the particular miracles depends on their relation to the Grand Miracle; all discussion of them in isolation from it is futile.

The fitness or credibility of the Grand Miracle itself cannot, obviously, be judged by the same standard. And let us admit at once that it is very difficult to find a standard by which it can be judged. If the thing happened, it was the central event in the history of the Earth—the very thing that the whole story has been about. .... It is easier to argue, on historical grounds, that the Incarnation actually occurred than to show, on philosophical grounds, the probability of its occurrence. The historical difficulty of giving for the life, sayings and influence of Jesus any explanation that is not harder than the Christian explanation, is very great. The discrepancy between the depth and sanity and (let me add) shrewdness of His moral teaching and the rampant megalomania which must lie behind His theological teaching unless He is indeed God, has never been satisfactorily got over.