In spite of the many differences among Christians, Jews and Muslims, they share a fundamental belief in God as compassionate and just. As a result, those communities have often nurtured people of extraordinary kindness and courageous commitment to justice. In contrast to the deep hatred that obviously inspired the September 11, 2001 attacks on the World Trade Center and the Pentagon, the vast majority of Muslims, like their Jewish and Christian counterparts, are appalled and sickened by terrorism, and utterly repudiate the mass murder of innocent people.
 Why then do some members of those same communities believe that it is their moral obligation to wage aggressive holy war, even to annihilate innocent people in God’s name? What aspects of their scriptures and traditions tend to support violence against “infidels”?
 Religion is clearly not the only catalyst of total war and other forms of indiscriminate violence. People seem to be able to invent all sorts of rationales for mass killing without feeling the need to cite the will of God. Some of the most appalling atrocities in history have been rooted not in religion per se but rather in racial or class hatred. There may even be a genetic tendency in our species (as in our chimpanzee relatives) to attack and kill others for no reason except that they aren’t “one of us.” (Wrangham and Peterson)
 But religious violence can take on a particularly intense and ruthless character, if the objects of that violence are seen as blaspheming or insulting God. The problem of indiscriminate holy war is particularly difficult for Judaism, Christianity and Islam to eliminate from within because it’s so deeply rooted in their scriptures and traditions.
 Most of my comments will be about Christianity, but I’ll start with the Hebrew Bible (or what Christians call the Old Testament), since it is considered sacred by all three traditions.
 Frequently in the Hebrew Bible, love of neighbor is directly commanded; in fact, love is to extend beyond one’s religious or ethnic kin to include resident aliens as well (Leviticus 19:17-18, 33-34). Murder and other forms of unjust violence are forbidden (Exodus 20:13). The primary ideas underlying those commandments appear to be: 1) God has shown compassion and mercy to you; show gratitude by being merciful to others; 2) human beings are created in God’s image; so treat them as such (Genesis 1:26-27, 9:6).
 One might infer from those ideas that no killing of persons would be allowed at all, that the obligation of love and the concept of human beings as made in God’s image would entail strict pacifism, an absolute duty not to kill people. But that is not what the ancient Hebrews concluded, since many offenses were subject to capital punishment (see examples in Exodus 21-22). So perhaps we might interpret the basic moral principle here to mean, All persons have a basic right not to be killed, but they can forfeit that right if they commit a serious enough offense. This would also be consistent with punishing only those who are guilty of crimes (Deuteronomy 24:16) and limiting the use of deadly force to the defense of the innocent.
 But collective punishment and indiscriminate war were also commanded or approved in the Hebrew Bible, especially in cases of idolatry (i.e., the worship of other gods). The first of the Mosaic commandments prohibited the Israelites from worshipping anyone but Yahweh. God demanded purity and strict obedience; idolatry and blasphemy were punishable by death (Exodus 20:3, 5). Non-Israelites who lived within the area believed by the Hebrews to have been promised to them by God were seen to pose a great temptation to them to abandon their faith. This led them to justify the slaughter of entire communities (Deuteronomy 20:10-18; Joshua 6:21 and 10:40). And their holy wars eventually inspired similar wars many centuries later by Christians who admired Old Testament warriors like Joshua.
 Of course, most Jewish people today would reject the idea of indiscriminate killing in the name of God.
 Matthew chapter 5 reports Jesus as saying: “You have heard that it was said, ‘An eye for an eye and a tooth for a tooth.’ But I say to you, Do not resist an evildoer. [I]f anyone strikes [or slaps] you on the right cheek, turn [and offer him] the other also…. You have heard that it was said, ‘You shall love your neighbor and hate your enemy.’ But I say to you, Love your enemies and pray for those who persecute you.” Three of the Gospels also say that he rebuked one of his disciples for using a sword to defend him at his arrest.
 By contrast, when Jesus spoke with Roman soldiers, he did not recommend that they abandon their profession in order to serve God (Luke 7). Now an argument from silence is risky, but it’s puzzling how Jesus would have reconciled the military profession with nonresistance to evil and love of enemies. Also, the Gospels portray Jesus as using some degree of force to eject the merchants from the Temple in Jerusalem (John 2:13-16). There’s even a story where Jesus seems explicitly to permit his disciples to carry swords and by implication to use them in self-defense, though that passage appears only in Luke 22 and is very ambiguous.
 Compare two Gospel stories of Jesus’ arrest:
Matthew 26: “Judas [led] a large crowd with swords and clubs [to arrest Jesus]. Suddenly, one of those with Jesus put his hand on his sword, drew it, and struck the slave of the high priest, cutting off his ear. Then Jesus said to him, ‘Put your sword back into its place; for all who take the sword will perish by the sword. Do you think that I cannot appeal to my Father, and he will at once send me more than twelve legions of angels? But how then would the scriptures be fulfilled, which say it must happen in this way?'”
 Note that Jesus gives at least two rationales here against his disciple’s use of his sword. One sounds like a piece of prudential advice: if you don’t want to be killed yourself, don’t use lethal weapons. The other rationale might be restricted to this situation only: the disciple must not interfere with Jesus’ divine mission, which includes his arrest and crucifixion.
Luke 22: When the armed mob led by Judas arrives, Jesus’s disciples ask, “Lord, should we strike with the sword?” Jesus does not respond before one of them cuts the servant’s ear off. Then Jesus says simply, “Stop! No more of that!”
 In Luke’s version there’s only a command with no supporting reasons. This might reflect an abhorrence of violence in general. But we might wonder why Jesus would permit his disciples to carry swords just a few verses earlier, yet forbid them to use them in his defense.
 Another curious aspect of all of the Gospel versions of Jesus’ arrest is that apparently nothing happens to the disciple who uses his sword. One would think that the armed group accompanying Judas would have at least arrested him, if not killed him on the spot.
 How did the early Christian community answer the question of whether force could ever be morally justified? Many of them seem to have believed in a dual ethic, one for Christians, the other for the state. I’ll use Paul, Tertullian and Origen to illustrate this.
 Those three influential Christians interpreted Jesus’ teaching and example to prohibit all uses of force by Christians, not only in self-defense but apparently even in defense of other innocent people:
 Paul wrote in Romans 12: “Do not repay anyone evil for evil, but take thought for what is noble in the sight of all. . . . Beloved, never avenge yourselves, but leave room for the wrath of God.”
 Tertullian wrote in his essay On Idolatry that when Jesus rebuked the disciple who defended him at his arrest, he in effect disarmed every soldier (or at least every Christian). In his Apology to the Roman rulers, he said that Christians believe it’s better for them to be killed than to kill. Elsewhere he stipulated that when soldiers convert to Christianity, they must leave the military.
 Origen asserted that Jesus prohibited homicide, and thus that Christians may never kill or use violence for any reason.
 But all three of those men also seemed to think that God authorized the state to use lethal force for certain purposes:
 Paul wrote in Romans 13: “Let every person be subject to the governing authorities; for there is no authority except from God, and those authorities that exist have been instituted by God. Therefore whoever resists authority resists what God has appointed, and those who resist will incur judgment. For rules are not a terror to good conduct, but to bad. Do you wish to have no fear of the authority? Then do what is good, and you will receive its approval; for it is God’s servant for your good. But if you do what is wrong, you should be afraid, for the authority does not bear the sword in vain! It is the servant of God to execute wrath on the wrongdoer.”
 Tertullian said, “We [Christians] pray for life prolonged; for security to the empire; for protection to the imperial house; for brave armies. . . .”
 Origen also claimed that although Christians won’t serve in the military, they offer “prayers to God on behalf of those who are fighting in a righteous cause, and for the king who reigns righteously, that whatever is opposed to those who act righteously may be destroyed.”
 In some respects these views are internally inconsistent: It’s not possible to rule out killing entirely, and then permit it on the part of the state. But the general point here is that these authors viewed strict pacifism as the only acceptable ethic for Christians.
 A significant shift in Christian thinking about war occurred in the fourth and fifth centuries, after Emperor Constantine began to use the Roman state to support the Church. According to an influential bishop named Eusebius, absolute nonviolence was from then on to apply solely to clergy, monks, and nuns; lay Christians would now be obligated to defend the empire with force. Ambrose, another important bishop of that era, thought that Christian love entailed a duty to use force to defend innocent third parties. He also shifted the focus of Christian moral concern from the act of violence to the attitude of the agent: Christian soldiers should love their enemies-while using deadly force against them! (Bainton; Swift)
 Augustine recognized that Jesus had taught things that seemed to entail strict nonviolence. But like Ambrose he believed that they applied to dispositions rather than actions. Christians are not only permitted to use force in defense of the community, they’re obligated to obey such orders from higher authorities. Augustine also came to accept the use of force against heresy, but believed that it was consistent with a benevolent desire of the Church to correct its wayward children.
 But Ambrose and Augustine also believed that there should be moral limits on Christian uses of violence. Even in cases where Augustine considered war to be the lesser of evils, he regarded all killing as ultimately tragic, always requiring an attitude of mourning and regret on the part of Christians (ibid.). Partly due to his influence, throughout most of the medieval period, killing in war was considered a very serious sin. If a Christian soldier killed an enemy soldier, even in a war that was considered just, the Christian soldier would have to do penance for the killing, usually by fasting and prayer for a year or more (Verkamp).
 We can also see the roots of the modern principle of “noncombatant immunity” develop in the medieval period when secular military ideals of chivalry combine with Christian decrees of protection for clergy, peasants, women and others who usually did not take part in combat. Thomas Aquinas added another important ethical consideration in stipulating that Christians may only use the minimal force needed to save lives from unjust attack. I sometimes paraphrase Aquinas in this way: Don’t use a shotgun if a baseball bat will suffice.
 But the medieval period also witnessed the emergence of total war in the name of Christianity. There was increasing glorification of the Christian knight, an identification of military courage and honor with Christian virtue. Consider how this German poem draws on the story of Jesus’ arrest:
Then boiled with wrath
The swift sword wielder
Grieved his heart that any sought to bind his Master,
Grim the knight faced boldly the servants,
Shielding his Suzerain,
Not craven his heart,
Lightning swift unsheathed his sword,
Strode to the first foe,
Smote a strong stroke,
Clave with the sharp blade
On the right side the ear from Malchus. (Bainton)
 The glorification of Peter here is of course somewhat ironic, in that Jesus rebuked him (or another disciple) for using his sword! But the poem also reminds us that if we had been with Jesus at his arrest, we might hope to have had the disciple’s courage and sense of moral outrage.
 Now by itself, military courage and honor might help to reinforce limits on war conduct, e.g., in the protection of noncombatants. But many of the traditional restraints on war advocated by the Church started to erode in the medieval period. In the ninth century, two popes declared that the sins of Christian soldiers could be erased if they died in defense of the Church; they would be guaranteed entry into heaven. And in the year 1095, Pope Urban II launched the First Crusade, urging European leaders to rescue the Holy Land from its Muslim occupiers. He referred to Muslims as a “vile race,” an “unclean nation” that had polluted Christian holy places, and called for their destruction. Killing Muslims became itself a form of penance for Christians for remission of their sins. Moral rules governing the conduct of war were abandoned. No one was immune from attack by Christian crusaders; whole cities were slaughtered (Halsall).
 Thus, ironically and tragically, a religion that began with the largely nonviolent teachings and example of Jesus evolved in its first millenium to the point where Christians came to wage total, indiscriminate war against heretics and infidels. Today, of course, most Christians would find total war morally repugnant, especially if waged in the name of God.
 In the Islamic tradition, the Qur’an repeatedly refers to God as compassionate and just. The Qur’an also says that “there is no compulsion in religion” (2:256), meaning that one’s submission to God must be freely chosen, not forced (Ali). The Qur’an urges Muslims to use “beautiful preaching” to persuade people to accept Islam, and to “argue nicely” with Jews and Christians who are seen as worshipping the same God as their own (16:125, 29:46, Firestone). The Prophet Muhammad was said to have practiced non-violence early in his prophetic career, but soon came to believe that God commanded the use of force, not only in defense of his growing religious community (Qur’an 22:39-40) but also in the form of offensive jihad to expand the territory of Islam. (Kelsay; Firestone)
 The word jihad, by the way, means struggle or effort. Jihad can refer to the struggle of the individual Muslim to conform his or her will to Allah’s, or to a peaceful effort to persuade others to accept Islam. But jihad can also mean holy war. In fact, there’s a sense in which the only completely just war in Islamic terms is a holy war, since it has to be approved by proper religious authorities and waged to defend or promote Islam or the Muslim community. (Kelsay; Johnson)
 In spite of the Qur’anic statement against forcing religion on others, Muslim leaders have sometimes threatened to kill unbelievers if they did not accept Islam (Peters). Although Islam spread to some parts of the world mainly by means of “beautiful preaching,” much of its expansion elsewhere was due to offensive war, first by Muhammad to unify Arabia, then by his followers in conquering the Middle East, North Africa, and so on. In fact, for many years the caliphs or Muslim political leaders were expected to wage offensive jihad at least once a year. (Johnson)
 However, Muhammad and his successors did express some important moral rules for fighting holy wars: women, children and the elderly were not to be intentionally killed (though they could be enslaved). Jihad was not supposed to be total war involving indiscriminate killing (in spite of what Osama bin Laden might claim). But Muslim leaders were permitted by Muhammad to kill all captured soldiers and most adult male civilians if they were not Muslims or if they had abandoned Islam. So Islam traditionally did not uphold a generic principle of noncombatant immunity, though many Muslim leaders today uphold such a principle, and have explicitly affirmed that in criticizing terrorism committed in the name of Allah. (Kelsay; Johnson; Peters)
 Tragically, some advocates of aggressive religious war can still be found today in all of the world’s major religions. What they cannot legitimately claim, though, is that their position is the authentic expression of their faith. Each of the three traditions I’ve discussed contains ethical principles that are incompatible with total war. But in order for members of those faith communities to continue to believe that God is compassionate and just, I think they must repudiate claims and values in their own scriptures and traditions that are incompatible with those ideas. It does not blaspheme or insult God to believe that God’s actions are limited by objective moral principles. To say that God would never condone or command total war or other cruelty does not represent a significant limit on God’s power.
 I also think that people of many different faiths, as well as those of no religious faith, might concur with the following ethical principles and rules:
1) All people have a prima facie right not to be killed. This right can only be forfeited if they intentionally try to kill innocent people.
2) Given the immense destruction and loss of life that war usually brings, all nonviolent means of realistically achieving just objectives should be tried first.
3) War should only be waged when necessary to protect the rights and welfare of the innocent.
4) Innocent civilians should not be directly targeted, even if doing so would end the war sooner.
5) Weapons and tactics should not be used against military targets in ways that are certain to cause civilian casualties, unless that is the only way to protect one’s own soldiers or civilians.
6) Captured soldiers should not be tortured or summarily executed but treated humanely.
7) Each side should be held accountable for any atrocities committed by its military forces.
 If these rules sound familiar, that’s because they’re derived from the Western “just-war tradition.” Many of them have also been incorporated into international treaties like the Hague and Geneva conventions. The just-war tradition rejects strict pacifism as insufficient to protect the innocent from unjust attack. But just-war rules, at least when applied in a careful and honest way, also guard against total war waged in the name of religion or any other cause.
 Religious communities can help to ensure that political and military leaders abide by these rules and inculcate respect for them in the training and management of soldiers. But just as importantly, faith communities can nurture firmly rooted habits and dispositions of compassion and nonviolence, reducing the likelihood and severity of war by dispelling the fear and hatred that too often inspire and escalate it.
Abdullah Yusuf Ali, The Meaning of the Holy Qur’an (1989).
Roland Bainton, Christian Attitudes toward War and Peace (1960).
Anthony Coates, The Ethics of War (1997).
Reuven Firestone, Jihad: The Origin of Holy War in Islam (1999).
Paul Halsall, collection of Crusade-era texts, http://www.fordham.edu/halsall/sbook1k.html.
Peter Harvey, “War and Peace,” in his Introduction to Buddhist Ethics (2000).
James Turner Johnson, The Holy War Idea in Western and Islamic Traditions (1997).
John Kelsay, Islam and War (1993).
The New Oxford Annotated Bible: New Revised English Bible with the Apocrypha (2001).
David Perry, recommended web sites on ethics and warfare, http://home.earthlink.net/~davidlperry/weblinks.htm.
Rudolph Peters, Jihad in Classical and Modern Islam (1996).
Louis Swift, The Early Fathers on War and Military Service (1983).
Bernard Verkamp, The Moral Treatment of Returning Warriors in Early Medieval and Modern Times (1993).
Richard Wrangham and Dale Peterson, Demonic Males: Apes and the Origins of Human Violence (1996).