Location, free association, whatever, has no bearing on whether actions of another constitute a threat against you that is legally actionable. What this case should be based on is whether the words uttered by the accused constitute a credible and specific threat by one individual against another. The scriptural texts quoted so far by various posters seem to be lacking in specificity. Can you distinguish the difference between "I'm going to harm you, Poobah, in such-and-such a way", and "the wages of sin is death", for example? I think a reasonable person could.
If someone barges onto my property...
You seem to be vesting a lot in the notion of your property. The article says the accused saw the accuser entering the clinic, so even that point is unclear. The courts have muddied the waters a bit on this issue by raising the notion of "public accomodation", like bars and diners. So at what point on those matters would you feel justified to claim as "your property" and employ deadly force? If someone came up to you on the sidewalk and read a Bible verse that you construed as a threat (which is wasn't), would that allow you to blow them away? Is the clinic a "public accomodation"? If this happened in a public place, maybe like a privately-owned mall or office building that you had an ownership stake in, would that suffice?
...shouting that the wages of MY sins are death, I'm going to make several decisions in very rapid sequence, and it is quite possible that I would make a decision in favor of decisively engaging a perceived threat with the intent of promptly rendering said threat harmless. Once that decision is made, I would employ deadly force against the threat.
Then you'd likely face appropriate criminal penalties, and rightly so, unless the threat was specific and credible. Simply stating that the wages of your sin are death, without a specific and credible indication that the person uttering those words was likely to be the agent of such an outcome and that such acts were imminent, your (lethal) actions probably would carry a heavy legal liability.
Generally, barging onto someone else's property, loudly shouting something at them, is a stupid thing to do in this day and age. And stupidity isn't a crime--but it has one punishment, which is awarded swiftly, ruthlessly, and without appeal.
Quite a barbaric and bloodthirsty thing to say. Look at the generality and vagueness in your words. You've implied that a loudly shouted word or phrase is grounds for lethal action. Fortunately, ours is a more civilized society, and the law offers appropriate sanctions against such barbaric and vigilante justice. If the person you fear comes into your private home uninvited and shouts "I'm gonna kill you, sucka!" and has a wild look about them and perhaps is brandishing a weapon, you'd probably be on safe ground to take lethal action (although, depending on things like race and income, you might be hit with legal actions nonetheless). However, if someone comes into your bar and shouts at you, "You know, you're one ugly honky!", and makes no further moves, but you kill him anyway because he shouted something at you on "your property", you're probably gonna go down in a big way. Your generalized statement places both acts on the same moral plane in terms of your permissible response(s), which is obviously not the case.
What this article likely shows, in essence, is that one individual was offended by another, and the offended party seeks to misuse and pervert the justice system to penalize the other person for their moral position. The nature of the offense seems to be rooted in the conflicting moral positions of each, and the tactics of non-violent protest, whicxh, in other venues, have been embraced and lauded by society as a means for bringing about peaceful change. Individuals and the government seem to be selectively (i.e., pro-life protestors) mobilizing against the free exercise of political speech, and that is dangerous to everyone. After years of protest and FReeping against Clinton, those on FR, more than most anyone else, should realize that.
Coming onto my property while doing so is frequently sufficient specific and credible indication of hostile intent. The intruder is intent on forcing a confrontation on private property while making a statement that mentions death, and generally acting in a belligerent, hostile manner. I've had to deal with people doing that (apparently, they feel they have a right to evangelize Catholics at 120 decibels while trespassing). On two occasions, I seriously considered employing deadly force.
I said that it is "quite possible" that I would use lethal force. It's not certain, and I haven't had to--YET.
Believe it or not, the old saw about one's right to swing one's first ending at someone's nose has got to be one of the dumbest lines there is. You may NOT swing your fist in the direction of my nose; doing so is going to result in an unpleasant reaction on my part.
Some of the pro-life crowd needs to get a clue. When someone does not want to talk to you, cast not your pearls before swine; better to shame them with silent witness against them.