A Civil War

Christianity agrees with Dualism that this universe is at war. But it does not think this is a war between independent powers. It thinks it is a civil war, a rebellion, and that we are living in a part of the universe occupied by the rebel.

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 a great campaign of sabotage.

--C. S. Lewis, Mere Christianity, Book 2, chapter 2