We believe that the death of Christ is just that point in history at which something absolutely unimaginable from the outside shows through into our own world. And if we cannot picture even the atoms of which our own world is built, of course we are not going to be able to picture this. Indeed, if we found that we could fully understand it, that very fact would show it as not what it professes to be — the inconceivable, the uncreated, the thing from beyond nature, striking down into nature like lightning.
You may ask ‘what good will it be to us if we do not understand it?’ But that is easily answered. A man can eat his dinner without understanding exactly how the food nourishes him. A man can accept what Christ has done without knowing how it works: indeed, he certainly would not know how it works until he has accepted it.
We are told that Christ was killed for us, that His death has washed out our sins, and that by dying He disabled death itself.
That is the formula.
That is Christianity
That is what has to be believed.
~ C.S. Lewis, Mere Christianity.