On Sunday, I preached on the Image of God. One of the observations I made, building on Genesis 9:6, is that because human beings are made in the Image of God, we respect them by taking their choices seriously. The man who murders his neighbor, who rapes a woman, who kidnaps a child is still himself made in the image of God and worthy of respect - the respect that says, "You are a human being who chose to commit a criminal act. We will treat you in accordance with your decision. We will not excuse your action by claiming that you were the victim of your childhood or your mistreatment or your biological composition. We will show you respect and execute you."
C.S. Lewis with his typical genius develops this observation in his essay "The Humanitarian Theory of Human Punishment." This essay is available in the book God in the Dock or online here. Lewis demonstrates the inhumanity of the supposed "humanitarian" theory of punishment which objects to capital punishment in particular and the concept of a person's "just due" in general; he effectively obliterates the foundation of the entire penitentiary system.