I have three young daughters and a 20 gauge shotgun. I have never fired it and pray to God I never will need to. But if my family's life is in immanent danger...
In such a situation, it is as being in a war, and my understanding is that mortally wounding another in self-defense or defending the life of the helpless against a would-be murderer is not an unforgivable sin. Would it require confession? Of course. Would it require penance? I would hope so. Does the Church anathematize those who have fought in wars in defense of their neighbors and families? I can't recall this being the case. In fact, we pray for those in the military in every Divine Liturgy and priests often bless soldiers prior to battle.
BTW, a shotgun is the best weapon for home defense. A 20 gauge is good because it can be handled easier by women. Just the sight of it or the sound of the 'chik-chik' is enough to make any intruder run for the closest exit (which is of course the main goal). The hope is that it will avert violence and if the assailant unfortunately chooses violence, it is a mighty weapon to have.
Edited by Antonios, 17 February 2011 - 09:31 AM.