Ethics Morality and "Sin"

Recently we heard a member of the NRA (National Rifle Association) address a group of students and parents on the subject of gun control. After the usual blah-blah-blah reasons why every American should pack an automatic weapon with a magazine of at least 20 shots to kill off the lethally homicidal deer population, he wrapped up with this thought:
"If someone breaks into your home, shoot to kill. Do not shoot to wound:
If the criminal lives, he or she will sue you."
Naïve fools that we are, we had imagined that most of the members of the NRA, and certainly of the audience of which we were a part, were Christians and thus would subscribe to the commandment, "Thou shall not kill."
The question that occurs to us is this: Was the speaker being ethical? Was he being moral? Or was he committing a sin by suggesting that we the audience break a "sacred" commandment?
Let us deal with the "sin" first. The commandment was written, we are given to understand, by a man (Moses), presumably at the behest of "God" or "Jehovah" himself. Should one regard written commandments as an absolute law? Should a religious law apply to all taxpayers in a nation founded by Enlightenment thinkers honoring absolute separation of church and state?
This is probably a good commandment, even though it is honored more in the breaking than in the usage. Mostly we obey the laws of the nation. We do not excessively exceed the speed limit on the highways or molest one another. Such laws are developed for the benefit of the whole of society.
We don't consider breaking them a "sin", though: It's merely a risk: the risk of being punished. So the arbitrary labeling of an act a "sin" probably has very little effect on our selection of the ethical set by which we choose to run our lives.
The question then becomes: When we recall the speaker who urged that we break the sacred law "Thou shall not kill", was he being moral? In our opinion the answer is "Of course not!" though in his own weird twisted way he probably thought of himself as a very upright, even exemplary citizen.
The killing of someone has a lower pain threshold for the killer than being sued. Where then do ethics come into this question? Are you "ethically" going to shoot the criminal--and shoot to kill, not to wound? It depends, of course, on what your ethical set really is. If you were brought up in a neighborhood of criminals, you will have an entirely different set of ethics than someone who was brought up in a good, friendly, "Christian" area. (Of course the two adjectives may be mutually exclusive.)
In America the murder rate is approximately 1000 times the murder rate in Japan and 100 times that of France; we are conditioned to think of life as being very cheap. So the ethics of American society permit acts which in those foreign societies would be anathema--unthinkable ... and memorably punishable.
If I go to the dictionary and look up morality and ethics, I find myself directed from ethics to morality and from morality back to ethics. Apparently the writers of our tomes don't know the answer either. The derivation of ethics in the etymological dictionary concludes with "a placing of oneself, hence self-assertion, self will, and habit relating to custom" and moral under "excellent in conduct"--and it is noted that the root of moral is "uncertain". So both ethical and moral relate to the way we conduct ourselves, but it is apparently up to each individual person to define their own level of "morality" and what is "ethical" behavior.
For most of us the dictionary definition is nothing like satisfactory. Many of us alternative individuals cannot and will not turn to the "bible" and St. Moses to improve the dictionary definition. We Frosts can suggest only that you try working out a definition for yourself. The thought of the Wiccan Rede might fleetingly cross your mind.
If it harm none, do what you will.