The “just war” idea is fine, when it is a defensive war, as in the Ukraine, when their land was invaded by an act of Russian aggression. Seems to give one a moral justification. However, how do Christian citizens of an aggressor nation deal with being called up to fight in an unjust cause? Maybe, some German soldiers during World War Two felt conflicted between their faith, and their patriotic duty? One wonders? Go fight for Hitler? The enemies included Jews, Poles, Czechs, French, anyone in the way of the Third Reich. Earlier in history, Augustine tried to walk that line, by assuring the Roman rulers that Christians were ready to fight, despite the knowledge that Rome was a brutal empire interested in conquest and colonialization as a divine right. Closer to home, our Spanish American War was hardly a just war either, and numerous other examples exist. In my view, as a veteran of the Vietnam War, it is not so easy to understand what constitutes the “national interests” of one’s native land, but we cannot worm our way through the problem of distinguishing a just war from an unjust one by relying on the two kingdoms idea. Within the conscience of each Christian sent to war to kill strangers is the moral choice to participate or not. If the war is unjust, than there is only one kingdom we must serve, and it is the Lord’s.