466. Why must human life be respected?Human life must be respected because it is
sacred. From its beginning, human life involves the creative action of God and it remains forever in a special relationship with the Creator, who is its sole end. It is not lawful for anyone directly to destroy an innocent human being. This is gravely contrary to the dignity of the person and the holiness of the Creator. "Do not slay the innocent and the righteous" (
Exodus 23:7).
Further reading: CCC 2258-2262, 2318-2320467. Why is the legitimate defense of persons and of society not opposed to this norm?
Because it is choosing to legitimately defend oneself in respecting the right to life (either one's own right to life or that of another) and not choosing to kill. Indeed, for someone responsible for the life of another, legitimate defense can be not only a right but a grave duty, provided only that disproportionate force is not used.
Further reading: CCC 2263-2265