Felix said:
Which is frustrating because there are times when killing is most certainly not wrong.
Try not to state this as fact. It isn't. For some people, killing is
always wrong. Period. For some people, killing is always wrong, but sometimes necessary.
FranktheDM admits the possibility of mercy into the world ("The worlds D&D takes place in have a place for mercy"), so it's not as if he's espousing a Kill 'em all mantra. He's just rejecting the idea that anyone in a DnD campaign world, violent and dangerous, would be able to survive unless they had the ability and willingness to kill if the situation demanded it. No, they don't have to exercise that ability often, but they must have it.
I imagine that quite a few of the inhabitants of the typcial D&D world (heck, let's go default Greyhawk here) never kill. Average peasant in the Free City of. . . probably not a killer. Maybe never even comes up in his life. Heck, some of them probably don't even kill their own food. Maybe in Frank's, umm, mentally sound world, everyone must live or die by the sword (or spell), but that's certainly not the assumption for my game setting. If it works for him, or for you, keen. But it's not the OTW of things.
And if you don't have the option of delivering him to justice, what do you do? Tie him up for his minions to free? Toss him in the bag of holding until he suffocates? Cut out all the unvital organs and leave him a useless bloody mess until a cleric with Heal shows up? Kill him and get it over with; you're saving the lives of the people he would have killed.
Or maybe your character has such a strong belief that he does whatever he can to deliver the now-subdued person to justice, even if it inconveniences him. Maybe he thinks "Kill him and get it over with" is the justification of the weak-willed who don't actually serve the cause of good, but instead seek rationalization for their own need to murder.
Nifty how different characters can approach things in different manners, isn't it?
I have played more than a couple of characters who refused to kill. Some refused to kill intelligent beings, but were cool with hunting animals for food, and I've played some who refused twouldn't do it himself, and wouldn't subdue someone for a party member to kill. I had one who actively preventted party members of delivering so-called "mercy killings". These characters didn't screw the party. Made them go out of their way sometimes, but didn't reduce their effectiveness. And I had one who refused to kill, and refused to let the party kill, but was not humble about it. Lorded his moral superiority over the group like a freaking hammer.
Now that guy, they didn't like. And they finally let him know they didn't like him by getting stabby with it. Several times. I certainly coulnd't deny that he was kind of asking for it.
So for those who think it just can't work, if you haven't tried it, don't dismiss the character concept right off the bat. It could result in some fun, or at least moderately interesting times. If you have tried it and it didn't work, I understand that not all concepts will work in all games. Believe me, I get that.
But regardless, maybe you could try and avoid saying it's stupid, or a mental sickness. Cause of all the things in the world that are, being unwilling to kill isn't.