I support the death penalty because I believe, if administered swiftly and justly, capital punishment is a deterrent against future violence and will save other innocent lives.
But secondly you say 'society must exact vengeance, and society must punish'. Wrong on both counts. Vengeance comes from the individual and punishment from God.
It isn't the desire to abide by the law that makes everyone behave as society requires, but the fear of punishment. Each one of us carries a gallows inside us.
It took the Church until 1832 to remove Galileo 's work from its list of books which Catholics were forbidden to read at the risk of dire punishment of their immortal souls.
If the people be led by laws, and uniformity sought to be given them by punishments, they will try to avoid the punishment, but have no sense of shame.