St. Augustine, a 4th century church leader, believed that war was always a sin, and if there had to be a war, it should be waged with sadness. Augustine went onto to write that although war was always the result of sin, war was also the remedy for sin and for the restoration of peace.
We do not seek peace in order to be at war, but we go to war that we may have peace. Be peaceful, therefore, in warring, so that you may vanquish those whom you war against, and bring them to the prosperity of peace.
However, Augustine would be the first to admit that war is a complex issue. How does one reconcile Jesus Christ’s call for his followers to be “peacemakers” as well as “rendering unto Caesar those things that are Caesars”? He stated that Christians did not have the right to defend themselves from violence, however they could use violence if it was necessary to defend the innocent against evil.
Augustine and later Christians, such as philosopher Thomas Aquinas, suggested four requirements for a just war.
Augustine referred to the Apostle Paul’s command that “Everyone must submit himself to the governing authorities, for there is no authority except that which God has established” (Romans 13:1). Augustine writes:
The natural order, which is suited to the peace of moral things, requires that the authority and deliberation for undertaking war be under the control of a leader.
Augustine did not consider a “proper cause” to be “. . . the desire for harming, the cruelty of revenge, the restless and implacable mind, the savageness of revolting, [and] the lust for dominating.”
He did argue that the rulers of states had an obligation to maintain peace, and this obligation gave them the right to wage war in order to maintain peace.
In the 13th century Thomas Aquinas clarified Augustine’s two principles:
It is necessary that the belligerents should have a rightful intention, so that they intend the advancement of good, or the avoidance of evil. The war must be fought with a good intention.
Over the centuries, other principles for a just war have been added:
A reasonable chance of success
Modern-day Christian philosopher and activist Charles Colson describes this third requirement: “Even if you have a good reason to attack, you cannot simply send young men out to die. Human life is too precious, too sacred to waste.”
Colson describes the fourth principle:
In waging a war, authorities must make sure that the harm caused by their response to aggression does not exceed the harm caused by the aggression itself. Annihilating the enemy in response to an attack on one of your cities is an example of disproportion.
Similarly, proportionality has also come to mean that non-combatants must be shielded from harm. They can never, for any reason whatsoever, be the targets of an attack. The history of modern warfare is characterized by “total warfare,” the expansion of targets beyond strictly military ones. That’s why, of all the requirements of just war theory, proportionality is the most likely to be violated, even by governments with the most just of causes/UL>
Christ warns that until He returns to establish eternal peace and justice, wars (just and unjust) are inevitable:
You will hear of wars and rumors of wars, but see to it that you are not alarmed. Such things must happen, but the end is still to come. Nation will rise against nation, and kingdom against kingdom (Matthew 24:6-7).
I have told you these things, so that in me you may have peace. In this world ou will have trouble. But take heart! I have overcome the world (John 16:33).>