This is a bit old, but I just came across an interesting piece by Melkite Catholic, Fr. Emmanuel Charles McCarthy, on Christian Just War Theory and Moral Laxism, which is a criticism of American Catholics with regard to the Iraq War.
Most articles of this sort, criticizing Christian involvement in matters of war, are rather poorly thought-out, in part because they tend to turn into poorly informed and rather misguided attacks on just war theory. What I like about this article is the recognition that the problem is not just war theory but casuistry, and that this, not just war theory, is the point at which to have a rigorous critique of participation in war. I think this is right. Just war theory, in either of its forms, is a general account of justice in war. Considering particular wars (and what to do about them) is not a matter of just war theory; it's a matter of applying principles to particular cases. In no moral arena do principles automatically apply themselves; in every case we have to exercise good judgment about how to classify particular cases, how certain and universal the principles really are, how strictly or rigorously we are to apply principles to them, how much tolerance for disagreement can be accepted as rational, etc. That's what used to be called casuistry, case-handling, before abuses led to the negative associations the word currently has. What Fr. Emmanuel criticizes is the tendency to laxism when wars are involved, and he's quite right about this. His criticism is therefore excellent food for thought. It isn't clear what system of casuistry he himself prefers, although from points here and there it seems that he is a probabilist.
In any case, it's a good example of the importance of casuistry for robust application of moral philosophy to the world, and it sheds some excellent light on many public disputes relevant to morality, many of which are really casuistical disputes that are not recognized as such. Debates about war are certainly one kind of such dispute.