Are you so arrogant to think that you can judge the woman who stopped (by killing the shooter) what would have been a slaughter and say she wasn't a Christian?
BTW, in her interview she praised God, gave Him the glory, and told of her prayer before engaging the enemy.
(Matthew 7:21) It is not those who say to me, Lord, Lord, who will enter the kingdom of Heaven but the person who does the will of My Father in Heaven. When the day comes many will say to me, Lord, Lord, did we not prophesy in your name, cast out demons in your name, work many miracles in your name? Then I shall tell them to their faces: I have never known you; away from me, you evil men!
You're doctrine of cowardly milktoast christians is a contradiction of Scripture. You ignore the passages that you disagree with and fail to reconcile them with applicable passages. This is how false teaching and apostasy starts.