As a general principle, I am opposed to killing people. I think it sets a bad precedent, for one thing (after all, somebody else might get it into their head to kill me). Then there's that whole Sixth Commandment thing, although many scholars allow as how it should most properly be read as "Thou Shalt Not Murder," not "Thou Shalt Not Kill."
Generally, the doctrine of "live and let live" pretty much sums up one major pillar of my personal philosophy. If you combine that with "do unto others as you would have them do unto you" you have, I think, a pretty even-handed--dare I say . . . liberal philosophy of life that would stand almost everyone in good stead in almost every situation.
Leave people alone who want to be left alone; help people who want to be helped; offer help to those who need it but maybe aren't ready to accept it yet, but don't press them to take help they do not want. How much better a world would we live in if everyone lived that way?
Unfortunately, the world is filled with people who do not want to leave other people alone, who want to help people who do not need or want help, and are willing to do almost anything to justify their behavior after the fact.
This is dangerous behavior.
In short, it pisses people off.
At some point, you have the problem of people who will not take "no" for an answer. "No, you can't have my goat." "No, you can't have my wallet." "No, you can't have my house." "No, you can't have my daughter." "No, you can't have sex with me right now."
What do you do with people who don't take "no" for an answer? What can you do? They won't let you "live and let live." They quite obviously do not believe in "doing unto others as you would have them do unto you."
Maybe, somewhere, in their own minds, they think they're helping you. They've convinced themselves that they know better than you how you should run your life, spend your money, use your belongings, conduct your sexual relations.
There comes a point where a man--or a woman--of peace will draw the line. That line is the one between the killing of another human as an act of evil, and an act of self-defense.
Where should that line be?
Should a woman, in imminent danger of being raped, be held guilty for killing her assailant? Should a man, seeing another man pull a pistol up to shoot him, feel guilty in pulling the trigger of his shotgun?
It seems to me that the line is the certain and imminent physical danger to you or to someone near you--then and then only are you justified in taking the life of the person who is offering that certain, imminent physical threat.
Anything less than that should be the domain of law, and of politics.
"Live and let live" goes both ways. It does not however require anyone to meekly acquiesce in being beaten, abused, of slaughtered by another person. Some people, and some acts, require a violent, deadly response.
And afterwards, people of good conscience will have to struggle with the aftermath, console the survivors and the friends and relatives of those who did not survive, and meditate upon the flawed and imperfect nature of the human animal.
And we will all go on. Somehow.