Natural isn't necessarily good, and revenge isn't a natural instinct to all. Furthermore, a revenge ethic perpetuates through society in such a way as to prevent peace and conciliation. Many murderers feel that they themselves are meeting out justice.

Far better, as Jesus attempted to do, to nurture an ethic to forgive. This is implausible in the face of murder, but we can reduce the glory of murder thorough a dismal life imprisonment.