Not understanding the atonement

This morning my son and I went out for breakfast and discussed a Chapter in C.S. Lewis, Mere Chrisitianity. We are up to Chapter 4, Book II, The Perfect Penitent. Which discusses the subtleties associated with understanding the atonement (i.e. what Christ's death achieved and how it did it). Lewis writes:

The central Christian belief is that Christ's death has somehow put us right with God and given us a fresh start. ....
Theories about Christ's death are not Christianity: they are explanations about how it works....
Jeans or Eddington [distinguished scientists of Lewis' time who also wrote popular books]. What they do when they want to explain the atom, or something of that sort, is to give you a description out of which you can make a mental picture. But then they warn you that this picture is not what the scientists actually believe . What the scientstists believe is mathematical formula.....
A man can eat his dinner without understanding exactly how 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.