As you may know, Platinum level members of the blog are allowed to make guest posts to their fellow Platinum members, and periodically they vote on one to be posted for all blog members. Here is the most recent winning post, by Dan Kohanski. (You may want to check out the benefits that accrue to the different levels of membership, and consider moving to a different level! Just go here: Register – The Bart Ehrman Blog )!
In this post Dan treats a perennially important topic: how ancient people (including biblical authors) understood the legitimacy of war, particularly in light of their specific historical and cultural contexts. What could be of more on-going relevance?
Dan will be happy to address questions and comments.
The history of how religions approach war is evidence that theology is a product of reaction to events rather than the application of eternal and unchanging laws. Look at the ancient Israelites, who lived in a period of endemic local wars, in which one petty kingdom after another (including those of the Israelites) made frequent attacks on their neighbors for territorial and monetary gain. Canaan was also the land bridge between Egypt and the empires of Mesopotamia. When those giants went to war, lesser nations such as Israel and Judah often became collateral damage. Small wonder, then, that the Hebrew Scripture assumes the legitimacy of war and dwells extensively on the rules for conducting one.
The earliest Christians, however, lived under the harsh but effective Pax Romana, the Roman peace. While first-century Judaea was often a violent place, it was the violence of rebels and bandits, rarely the clash of armies. Roman legions, brutal as they were, made travel reasonably safe, provided good communications, and ensured that no outside forces would trouble the peaceful life of imperial subjects and citizens. Jesus could therefore preach a pacifist attitude. “Do not resist an evildoer,” said Jesus. “If anyone strikes you on the cheek, turn the other also” (Matt. 5:39–40). Later in Matthew, Jesus warns that “all who take the sword will perish by the sword” (Matt. 26:52). Revelation describes a clash of supernatural forces, the embodiments of good and evil, but promises that the faithful in Jesus will be rescued before the battle begins. “I will keep you from the hour of trial that is coming” is the reassurance to be given to the church in Philadelphia (Rev. 3:10). True Christians would be passive spectators in the great cosmic battle, much as the righteous were in the book of Daniel (Dan. 12:1).
The Pax Romana made such a position feasible. In addition to that, I suggest that pacifism was a reasonable position for early Christians to take, given that they believed the world as it then existed was about to end at any moment, rendering earthly conflicts meaningless. And Christians read the Scriptural injunction “Thou shalt not kill” to mean an absolute prohibition on taking human life, even in self-defense. Over the next two centuries, Church fathers would cite this injunction when insisting that Christians could not serve in the Roman army, certainly not in combat roles. Although some historians have argued that the military’s use of what Christians saw as idolatry was why they avoided army service, this appears to have been a secondary reason.
As might be expected, others in the empire resented what they saw as a dereliction of duty on the Christians’ part. The third-century theologian Origen had an answer to “those enemies of our faith who require us to bear arms for the commonwealth, and to slay men.” Origen argued that “none fight better for the king than we do. We do not indeed fight under him, although he require it; but we fight on his behalf, forming a special army—an army of piety—by offering our prayers to God” (Origen, Against Celsus 8.73).
Yet in spite of this theological insistence on pacifism, increasing numbers of Christians did join the Roman army, especially the eastern army, in the third and fourth centuries, though hard numbers are difficult to come by. Then, in 312 CE, Emperor Constantine won the Battle of Milvian Bridge after ordering his soldiers to paint a Christian symbol on their shields. The following year, he made Christianity a licit religion, and in 380 Theodosius I made Christianity the official religion of the empire. By the early fifth century, anyone who was not a Christian was barred from military service. The defense of the empire was now in the hands of a Christian emperor leading an army of Christians; pacifism was no longer a practical option. Christianity needed a new theology of war.
Roman philosophers as far back as Cicero (106–43 BCE) had been exploring the question of what constitutes a just war. In the years after 380 CE, Bishop Ambrose of Milan relied heavily on Cicero in particular in his search for a way to allow Christians to kill their enemies in battle. By 420 or so, Ambrose’s protégé, Bishop Augustine of Hippo, had expanded his mentor’s work into a theology of just war that would guide the Church for the next several hundred years.
The two bishops insisted that a just war must be defensive, with mercy for the defeated, and that the true evils in war were “the desire to do harm, cruelty in taking vengeance . . . the lust for domination” (Augustine, Against Faustus 22:74). One must not, in other words, wage war with passion, but instead with love, and it must be waged only “at the command of God, or of some legitimate authority” because sometimes war is necessary “so as to preserve the order of civil peace” (22:74, 75). A just war, in short, was a necessary evil undertaken to maintain or restore moral order in the world. Augustine even turned Jesus’s admonition not to resist an evildoer into permission to use violence if one had the proper mindset. Jesus had said this, Augustine argued, “to prevent us from taking pleasure in revenge, in which the mind is gratified by the sufferings of others, but not to make us neglect the duty of restraining men from sin” (Augustine, Epistle 47.5).
But Augustine also had to come to grips with Biblical wars such as Joshua’s conquest of Canaan, which was anything but defensive, anything but limited, and which was waged with great passion. He found himself having to admit that such a war, even to annihilation, might still be justifiable. “By reason of the fact that God had commanded this, it must certainly not be considered cruelty that Joshua left no living thing in the cities that were handed over to him” (Augustine, Questions on the Heptateuch 6.10). In discussing this passage, Christian Hofreiter observes that “for Augustine, the justice of God is axiomatic; it is something he argues from rather than for” Therefore, “Augustine’s reading of the ḥerem [destruction] commands, his commitment to divine command theory, and his emphasis on human obedience lead him to chastise the Israelites in several places for not totally annihilating the Canaanites. In none of these instances does he consider the morality of the command itself.”
In my view, neither Augustine nor anyone else has ever completely succeeded in theologically reconciling God’s exhortation to war in the Old Testament with God’s prohibition of war in the New. (Think of the controversies over Quaker and Mennonite insistence on nonviolence and the troubles that conscientious objectors face.) The historian’s explanation that these theologies were each responses to conditions of their time is not one that a theologian may be comfortable with. But it is the one that fits.
 There is some disagreement among scholars over the extent of early theological opposition to war. See Simpson, Gary M., “”Thou Shalt Not Kill”–The First Commandment of the Just War Tradition,” Faculty Publications (2004), (https://digitalcommons.luthersem.edu/faculty_articles/297), 250n4.
 In De Corona X, Tertullian discusses the problem of idol-worship in the army, but in the next chapter he cites Matt. 26:52 as the main reason why no warfare is proper for Christians. See Bainton, Roland H., “The Early Church and War,” The Harvard Theological Review Vol. 39, No. 3 (Jul., 1946), 189-212 (https://www.jstor.org/stable/1508114) 192; 200-01.
 See, generally, Bainton; see Blin, Arnaud, War and Religion: Europe and the Mediterranean from the First through the Twenty–first Centuries. Oakland, CA: University of California Press, (2019), 43.
 See Blin (63-67); see Swift, Louis J., “St. Ambrose on Violence and War.” Transactions and Proceedings of the American Philological Association 101 (1970): 533–43 (https://doi.org/10.2307/2936070).
 See Swift (1970, 541 and 541n24).
 Hofreiter, Christian, Making Sense of Old Testament Genocide: Christian Interpretations of Herem Passages. Oxford UK: Oxford University Press (2018), 115 [emphasis in original]; 116.