Liked this comment from Brian McLaren:
On war … my interest has not been in figuring out if war is ever justifiable, but rather in how war can be prevented. History teaches that one of the worst ways to prevent war is by beginning with justifying hypothetical wars. Obviously, I’d be much less against a war in which people defend themselves from unprovoked invasion or aggression than I would elective or aggressive wars. But even there, I’d rather use the words “less against” than “justified.”
However, it still leaves the conversation somewhat in the hypothetical realm. I would say the more concrete question for many is this: is it ok for a Christian to enlist in the army, given that, once you enlist, yet get no choice over which wars you fight?