Regarding the gun violence, my point is that there are plenty of other causes of very preventable and tragic deaths that deserve attention in society.
Re: Moral Realism. I think you'd agree, being a moral realist, that killing a baby is wrong. What about if killing that one baby saved ten others? All of a sudden it's not quite so wrong.
My point is that something that may indeed be wrong in most if not all contexts, such as killing a person, is not in fact wrong or morally reprehensible in other contexts, say if that person is trying in fact to kill you. There is a lot more to this argument, and if you are interested in reading about it I would suggest reading Hume , "An Enquiry Concerning the Principles of Morals", it's a fairly short read that makes a far better case than i ever could.
I completely agree with you that using ambulances, mosques, and hospitals for offensive purposes is a very reprehensible thing to do given the current situation, and IMO that is not something that can be excused on the basis of moral relativism in the current situation. Furthermore, killing journalists and even killing the Americans in iraq I would describe as bad, they are actually trying to help you. In no way has moral relativism lead to this, it is in fact moral realism that is at fault. The jihadists, like the neo cons, believe in a great "Good" and "Evil", it is just largely opposite. They use this realist viewpoint to justify all of these killings because these people, regardless who they are, or what they doing, are not true muslims (true being the key), and thus deserve to die. If they were realtivists, they would see that the journalists, the iraqi police, and even the americans are trying to help them, and would find killing them a horrible thing to do (as I do).
Regarding your comments about the moral right and duty to defend ourselves; I am not quite sure if I can agree with that. I mean, let us say that you and your wife and daughter are being held hostage, and one of gunman goes to you, holds a gun to your head, and says he is going to kill you, but if you resist, then the others will not only kill you but your wife and daughter. I am sure that you, as I, would take it for their sake.
My point regarding all of this, and it is not meant as an affront to you, is just that there is no great list of "Good" and "bad" things, it all depends on the circumstances surrounding it. That does not mean you can excuse anything, indeed not, there ARE still good and bad things, their exact nature just changes with the situation (one final example, killing civilians is usually considered wrong, killing a civilian who is carrying explosives is something that I would personally consider to be fine). Both the Jihadists and the neocons use a realist moral structure to justify what they are doing, not a relativist.