Lewis explains that God created the world good, but evil perverted it. Evil is a perversion of the good, therefore it is not independent, and it doesn’t share an equal footing with God. Therefore, dualism is not true. These are the only two views with respect to the question of why there are a lot of things wrong with the universe: Dualism and Christianity – but only the Christian view makes sense. This is the Christian view: God created the world in the beginning, and it was good, but there was an “invasion”, so bad things happened and continue to happen.
I love this quote:
“Enemy-occupied territory – that is what this world is. Christianity is the story of how the rightful king has landed, you might say landed in disguise, and is calling us all to take part in the campaign of sabotage. When you go to church you are really listening-in to the secret wireless from our friends: that is why the enemy is so anxious to prevent us from going.”