Q&A: Death penalty is biblically valid. Genesis 9:5-6 (pre-Mosaic, given to all humanity): whoever sheds man's blood, by man his blood shall be shed — because man is made in God's image. Society has a mandate to execute justice. Romans 13:4: government bears the sword as God's servant/avenger. The sword = general governmental authority, which includes capital punishment for murder under certain conditions.

Genesis 9:5-6: pre-Mosaic (Noahic) command to all humanity — the death penalty for murder is a divine mandate because humans bear God's image. Murder is a strike against God's image. Romans 13:4: the sword is general governmental authority, but includes capital punishment. Caveat: guilt must be certain — not just probable. Self-defense and manslaughter are different categories.