As Christians, our primary concern is the glory of God. God is the standard who defines for us what is moral and immoral. We believe that the chief end of man is to glorify God and to enjoy him forever. We believe that we will all give account to God. We are morally responsible beings. Thus, our personal concern is to act in a manner morally pleasing to God. Christians also believe that legitimate authorities actually exercise God’s authority in the world when they act justly. Therefore, God is glorified when human governments wage just wars.
Just war theory is opposed to “realism” or “realpolitik” on the one hand (as exemplified by Machiavelli) and “pacifism” on the other. The former rejects moral constraints while the latter misconstrues them. Realism says that moral considerations are unnecessary; the only important thing is to win the war by whatever means necessary. Pacifism says that war is always evil. Both are biblically wrong.
The Classic Criteria
Ius ad Bellum – “Justice toward war.” When is it just to enter into war?
- Just cause. We may engage in war primarily for the defense of the common good (order, justice, and peace), which would include self-defense (e.g. Num 21:21-30), recovery of what has been wrongly taken (e.g. Gen 14), and punishing evil (Rom 13:4).
- Proper authority. Public authorities have the responsibility to secure and protect the public good of a just and orderly society. It is this responsibility which gives them the authority to declare war (Rom 13:1-4). Private parties do not have the authority to enter into war (Rom 12:19).
- Right intention. This has to do with both proper motive and with proper goals – the establishment of a just peace (Ps 34:14; Rom 12:18). Such concerns also extend to what happens after the war itself has ceased.
There are also some lesser criteria which are taken into consideration, such as reasonable hope of success, overall proportionality, and last resort. These are prudential judgments and are not primary moral criteria. In other words, they help to determine when it is wise to go to war, but they do not determine whether or not it is just to go to war.
As can be seen from these criteria, wars of aggrandizement and aggression are unjust. So are wars waged without proper authority. Wars which do not intend to establish or re-establish justice and peace but are waged because of anger, animosity, revenge, rebellion, greed, power-lust, and so forth, are unjust.
- Discrimination (noncombatant immunity). The force of war must be directed at combatants and not intentionally directed at noncombatants. The distinction between combatants and noncombatants is not always clear.
- Proportionality. The amount of force used in war should be proportionate to what is necessary to achieve the military aims with the least amount of bloodshed and destruction (e.g. Deut 20:10-15, 19-20).
In Christian perspective, these just war criteria proceed from love (Mark 12:29-31; Rom 13:8-10). The ultimate reason for a Christian to go to war is love for God and neighbor. We love God, so we want his righteousness and justice to prevail. When we bring justice to the evil-doer, we are enforcing God’s righteousness. We love our neighbor, so we will defend life while trying to do so in a manner that minimizes death.
Justice - Justice from a Christian perspective may be considered the application of God’s righteous judgment by God’s ordained authorities. It involves retribution and restitution.
Peace – Rightly ordered tranquility, not merely the absence of conflict
Love – Commitment to what is best for another.
Some Introductory Resources
Calvin, John. Institutes 4.20.10-12.
Charles, J. Daryl. Between Pacifism and Jihad: Just War and the Christian Tradition. Downer’s Grove, IL: InterVarsity Press, 2005.
Cole, Darrell. “Good Wars,” First Things, October 2001.
Davis, John Jefferson. Evangelical Ethics. 2nd edition.
Elshtain, Jean Bethke. Just War Against Terror.
Johnson, James Turner. “Just War, As It Was and Is,” First Things, January 2005.
Pavlischek, Keith. “Just and Unjust War in the Terrorist Age,” The Intercollegiate Review, Vol 37 No 2 (Spring 2002), 24-32.
Phillips, Richard D. “The Christian View of War.” Sermon preached 26 August, 2006. Available at SermonAudio.com. Accessed 6 March, 2008.
________. “The Christian Idea of Valor.” Sermon preached 26 August, 2006. Available at SermonAudio.com. Accessed 8 March, 2008.
 A common error among just war theorists is to claim that natural law apart from religious considerations is the basis of just war theory. This claim is inaccurate, if for no other reason than that no one ever thinks or operates apart from religious reasons. Religious neutrality is a myth. Theorists make this claim in order to bolster their point that just war applies to everyone, regardless of the religion they profess to believe. Just war does apply to everyone, but this argument is a wrong foundation. The true foundation, and the true reason that just war thinking applies to everyone, is that everyone is accountable to the one true and living God revealed in the Bible whether they believe it or not. Christians follow Jesus Christ as Lord and derive their just war principles from his authority. When unbelievers happen to get some of these principles right (because these principles are built into the nature of the universe that God made and governs), then believers and unbelievers become tactical partners in just war. But we are never strategic partners in just war, for we have different foundations and different goals.
 Note that these criteria are not the same thing as international laws or customs governing war. Just war criteria are moral criteria. Hopefully international laws based upon treaties and customs would reflect these moral principles, but they do not necessarily do so.
 “The service of private ends by private persons manifests cupiditas – wrongly directed, self-centered love or motivation – while efforts by those at the head of communities to serve the good of those communities show the effect of a concern for justice informed by caritas, rightly directed love” (James Turner Johnson, “Just War, As It Was and Is,” First Things (Jan 2005), available at http://www.firstthings.com/article.php3?id_article=142, accessed 25 January 2008).
 “When Thomas Aquinas discusses just war in the Summa Theologiae (II-II.40), he does not do so in the section on justice, but rather in the section on charity-specifically, the love of God. He makes it clear that war is not a vice that is opposed to the love of God. On the contrary, war-making, when just, can be a form of love. Of course, war is always contrary to peace, but this is sometimes desirable, since peace is not always a just order that deserves to be preserved. Nazi Germany, for example, provided peace and order for most of those in conquered countries who were willing to accept Nazi rule. But no one wishes to argue that the peace provided by Nazis is the sort of peace we ought to preserve. War, for Aquinas, can be a means to a just peace as well as a means to destroy an unjust peace (such as one established by Nazis). We keep a just peace and fight just wars because these are acts of charity. Just soldiering, in other words, is something Christians ought to do out of love for God and neighbor, and thus it is the most “human” thing we can do in certain circumstances” (Darrell Cole, “Good Wars,” First Things (October 2001), available at http://www.firstthings.com/article.php3?id_article=2243, accessed 4 March, 2008).