Lewis explains that in his view the “grand miracle” is the incarnation of God in Christ. That is, the physical coming of God as the son into a man’s body through human birth. The reason he believes that this event is the pivotal, central miracle (the “Grand miracle”) is because every other miracle is a preparation for, exhibition of, or a result of that one event. In other words, every other miracle that we can see recorded actually points ahead, inwardly, or retrospectively to the incarnation.
If that is true, then in that light, it is the obvious conclusion that the incarnation can be granted such a title as “the grand miracle.” Lewis defends against Hume’s logical arguments attacking the possibility of miracles using logic. One humorous defense he used addressed Hume’s argument that if it is only said to have been observed only happening once, it is extremely improbable that it happened at all. However, we only observe the whole of history to have happened once, but we do not question its probability, or even consider it to be a thing of amazement.
He goes on to explain how certain other concepts dealing with nature, sin, the trinity, and religion which may at times be difficult, fit into this idea. He is very thorough and the details of his arguments are really very extensive. They can help us gain perspective on our life from a very philosophical, yet in the end, practical perspective.
If one does accept the grand miracle, it would indeed not be philosophically responsible to reject such miracles as Christ’s calming of the storm. Some may argue that a miracle of such sort would throw the balance of nature off kilter. However, if Jesus was God, it only makes logical sense that he would be able to perform such an act. As creator of the universe, natural situations are ultimately orchestrated by Him and are hereby subject to his instantaneous manipulation. Nature simply adapts to the new situation, which makes sense because there is really nothing unnatural about it.
Lewis gives the analogy of closing a window to calm the immediate storm in a house. By doing so he has manipulated the natural storm into a peaceful calm, as the storm outside no longer affects anything indoors. Obviously, though, nature is not thrown off balance; it merely adjusts as if nothing happened. Similarly, when God changes certain affects of the natural state of the earth, nature “digests” the change and moves forward, so to speak.
To reject the ability of Jesus, given he was the incarnate God, to perform such miracles would be to reject him as creator. He who creates must obviously have total rule over his creation, or at least has the authority to make changes. A miracle such as calming the storm is nothing new for God; he controlled the weather all the time in the Old Testament. Therefore, if one accepts Jesus as God he must accept that Jesus was attributed all of God’s authority.