Neither the Church nor the Christian has any need for war in order to accomplish all that Jesus created them for and chose them to do in this life. Indeed, war is radically hostile to all that the Church and the Christian are, should be and should be about. War represents the concentration of everything that is irreconcilable with the will of God as revealed by Jesus. There are certainly evils other than war, and war—in preparation and in execution—brings all of them into human existence in spades. This is not the task Jesus assigned to His Church or to those He chose.
No Christian—bishop, priest, minister or layperson—can Christianize war by his or her participation in it, anymore than a Christian by his or her participation in a brothel can Christianize a brothel. Can a Christian morally choose to participate in a brothel as a strategy to save the immortal soul of another person working there? If not, then how can a Christian morally participate in a war to save a piece of land, an economy, a political system or the Dauphin? For, if one cannot morally change or modify or set aside the teachings of Jesus regarding God’s will for the greater task, to save an immortal soul, a fortiori, one cannot morally change or set aside or modify the teachings of Jesus to do the lesser task, save a mortal, totally perishable entity, e.g.the state, democracy, capitalism, communism, etc.
How long, O Lord, how long?