C.S. Lewis's "The Lion, the Witch and the Wardrobe" series reflects his views on Christianity. Specifically, the books are written as simple hero's journeys that deal with the theme of good-versus-evil.
The lion represents good while the witch represents evil. The lion's character is omniscient, nurturing, and long-suffering. His journey closely parallels that of Christ's in the New Testament.
The witch's character is vengeful, self-involved, desperate and destructive. Her journey parallels that of Satan.
It is important to have this strong contrast between these two characters so that the young reader can readily identify them and understand the issue of imbalance versus balance.
When the world is out of balance, in the first book, it is always winter and never Christmas. The reader immediately understands how terrible that is! When the world is in balance again, Spring comes -- representing the restoration of life and harmony.