One can learn a lot about a tradition by paying attention to how it answers the question, Is it ever right to kill? What we find when we survey world religions are teachings that are at least paradoxical, and in some cases downright contradictory. Every major religious tradition regards life and especially human life as sacred in some sense, and affirms mercy and compassion as basic human obligations. But influential religious authorities have also taught that it's sometimes right to kill other human beings. Some have gone so far as to rationalize wars of annihilation against heretics and 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. (Think of the 20th-century victims of Hitler, Stalin, Mao and Pol Pot.) There may even be a genetic tendency in our species, like that of 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, and thus as enemies of God who must be humbled or destroyed. This way of thinking continues to spark violence in countries as diverse as India, Pakistan, Sri Lanka, Nigeria, Ireland, Indonesia, and the former Yugoslavia.
I'm hopeful, though, that some ethical principles can be affirmed by all of the world's major religions to limit violence even when it can't--or shouldn't--be prohibited completely.
I'll begin my survey with Eastern faiths. One of the oldest living religions is Hinduism. The Hindu tradition reveres all of life, and affirms an ethical principle of ahimsa or avoiding injury to any sentient creature (Klostermaier). This ethic has often led Hindus to adopt vegetarianism and strict pacifism, and has been especially strong in Buddhism and Jainism, both offshoots of Hinduism. The pacifist ethic nurtured by these faiths lives today among the followers of Mahatma Gandhi and renowned Buddhist teachers like the Dalai Lama of Tibet, Thich Nhat Hanh of Vietnam, and Maha Ghosananda of Cambodia.
Buddhism stresses the need for people to constantly be aware of how hateful and greedy emotions can arise in order to avoid being controlled by them and lashing out violently against others. Buddhism seeks to undermine social divisions like the Hindu caste system, while at the same time reinforcing its virtue of compassion and the obligation of non-injury. As a result, the duty not to kill people or other sentient animals applies to all Buddhists, though as an absolute duty it has often been restricted in practice to Buddhist monks and nuns. (Harvey)
How would pacifists within these faiths respond to a concern that nonviolence might have little or no persuasive effect on a violent enemy, and could result in the destruction of one's community? Some contend that violence only seems to be effective, but usually ends up producing merely more violence. Others admit that nonviolence sometimes does not succeed in deterring or ending violence, but also claim that success is not as important as doing the right thing. (The Christian pacifist John Howard Yoder made the same point.)
Hindus and Buddhists believe in the Law of Karma, which rigorously enforces justice through an indefinite series of rebirths. So even if evil people succeed in their present lives, they'll pay for it in their next life. Trusting in the Law of Karma can help to motivate adherents of these faiths to overcome selfishness and hostility and resist succumbing to violence. (This functions similarly to the Western belief in a heavenly reward for living a devout and moral life, even if one suffers great injustice during one's earthly life at the hands of evil people.)
In practice, though, Eastern traditions often permit some exceptions to the general rule against killing. In mainstream Hinduism there is an entire caste of warriors, the Ksatrias, whose role in defending the community with force is considered to be just as important as that of the Brahmin or priestly caste. If a Hindu man is born into the warrior caste, he is obligated to kill enemy soldiers in defense of the community; his social role does not permit him to be a pacifist. He must kill with the proper disposition, though, without greed or anger. (Read the "pep talk" given by the god Krishna to the reluctant warrior Arjuna in the Bhagavadgita.) Some Hindu gods like Indra are believed to have warlike characteristics themselves, and are praised for destroying the enemies of orthodox Hindu teachings and practices. (Klostermaier)
On the other hand, total war in the sense of indiscriminate killing has typically been forbidden. Hindu soldiers are not to kill unarmed prisoners or civilians, apparently due to a sense of chivalry: it would be considered unprofessional for a Hindu soldier to harm defenseless people (Klostermaier).
Some Buddhists have argued that killing can be justified in rare cases as the lesser of evils, if the Buddhist community or other innocent people are threatened by violent attackers, and nonviolent means of persuasion and protest do not succeed. Interestingly, even when war might be waged with just cause and as a last resort, Buddhists still regard it as inherently sinful. (Harvey)
We should not infer, though, that Hindus and Buddhists have never engaged in total war or other indiscriminate killing. Many of their leaders have openly advocated aggressive violence against people of competing religions. Zen Buddhism was distorted in Japan to support a ruthless warrior ethic before and during WWII. Some Buddhists in Sri Lanka have promoted the "ethnic cleansing" of Hindu Tamils from the island. An influential Thai monk claimed in the 1970s that killing communists would actually produce karmic merit. (Harvey) And the man who assassinated Gandhi in 1948 was a member of a radical Hindu sect that opposed any political compromise with Islam or other faiths. But of course it's very difficult to see how such things can be justified in light of their religions' core values.
Frequently in the Hebrew Bible (or what Christians call the Old Testament), love of one's neighbor is said to be a fundamental duty; 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 is loving; imitate God's love; 2) God has shown compassion and mercy to you; show gratitude to God by being merciful to others; and 3) human beings are created in God's image; treat them as such. (See Psalm 145:8-9, Micah 6:8, and Genesis 1:26-27, 9:6).
If we considered those ideas in isolation from some other biblical values and commandments, we might infer an ethic of strict pacifism toward human beings, an absolute duty not to kill people, since even killing murderous attackers might be regarded as a kind of sacrilege as well as contradicting love. But that's not what the ancient Hebrews concluded, since murder and other serious offenses (Exodus 21-22) were subject to capital punishment. Genesis 9:6 says, "Whoever sheds the blood of a human, by a human shall that person's blood be shed; for in his own image God made humankind."
We might interpret that in modern terms to mean, "All persons have a basic right not to be killed, rooted in their having been created in God's image; but they can forfeit that right if they commit a serious enough offense." So far, this would only permit those who are guilty of certain crimes to be executed, i.e., strict retributive justice. Deuteronomy 24:16 states, "Parents are not to be put to death for their children, nor children for their parents; each one may be put to death only for his own sin." And if this ethic permitted war at all, it would seem to limit it to the defense of the innocent against unjust invaders, or punishing their atrocities.
But collective punishment and indiscriminate war were also commanded or approved in the Hebrew Bible, especially in cases of idolatry. 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 20:16-18 says, "[In] the towns of the nations whose land the LORD your God is giving you as your holding, you must not leave a soul alive.... [Y]ou must destroy them ... so that they may not teach you to imitate the abominable practices they have carried on for their gods...." Joshua 6:21 and 10:40 claim that "[Joshua's army killed everyone in Jericho], both men and women, young and old, oxen, sheep, and donkeys.... Joshua defeated the whole land... he left no one remaining, but utterly destroyed all that breathed, as the LORD God of Israel commanded."
Israel's external enemies were to be treated somewhat more leniently: they were first to be presented with peace terms, and if those were accepted then the people would be subjugated, not killed. But if they rejected the terms, the men would be slaughtered and the women and children enslaved. (Deuteronomy 20:10-15)
However, the later rabbinic commentators who compiled the Talmud relegated wars of annihilation solely to the specific divine commands connected with the ancient conquest of the Promised Land. (Theological questions about their consistency with God's compassion remained, of course: how could a loving God ever order the annihilation of whole communities?) But the Talmud also gave explicit permission for individuals to kill murderous pursuers, either in self-defense or in defense of others, based primarily on Genesis 9:6 (though that verse seems to apply only to a murder that's already occurred). Maimonides even thought that killing could be required in light of his reading of Leviticus 19:16, "Don't stand idly by the blood of your neighbor." (Broyde)
Defensive war was permitted on those grounds as well, and required if the survival of a Jewish state were threatened. Pacifism was only recommended as a prudential option, when using force against oppression or invasion would likely result in significantly more harm to the community. Even when just cause for war exists, Maimonides and most other rabbis urged that nonviolent efforts to achieve justice and maintain peace be pursued first. If war begins, destruction should not exceed what's minimally necessary to achieve important military objectives. And innocent lives should be spared whenever possible. (Broyde)
Drawing in part on these elements in the Jewish tradition, the contemporary Code of Ethics of the Israeli Defense Forces requires soldiers to use minimal force and to spare civilian lives, and also affirms the importance of respecting their dignity, property, values, and sacred sites. Clearly a war of annihilation like Joshua's would not be permitted under the IDF Code. But in practice the Code has not always been upheld in Palestinian areas, nor during Israel's invasion and occupation of Lebanon during the 1980s. Israeli military force is not always discriminate or proportionate; whole families of individual terrorists are often punished collectively (e.g., their houses are bulldozed); and Palestinian civilians are intimidated and humiliated on a daily basis. Of course, many Jewish people in Israel and elsewhere have criticized these tactics on moral grounds.
Turning to the Christian New Testament, one question that has been the subject of considerable debate is whether Jesus was a pacifist. Some passages in the Gospels seem to clearly imply that, but others are more ambiguous.
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 intimidation or 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.
Similar puzzles emerge from the stories of Jesus' arrest. The four Gospels agree that when Jesus was arrested by an armed group, one of his disciples drew a sword and wounded a servant of the high priest. But the Gospels differ about what was said during that incident:
In Mark's version of the story (14:43-52), Jesus says nothing to the disciple who inflicts the wound. Mark's gospel is thought by scholars to be the earliest of the four, and probably familiar at least to the writers of Matthew and Luke. But only Mark's gospel suggests that Jesus was silent at this point.
In Luke's account (22:47-51), alone among the gospels, Jesus' disciples first ask him, "Lord, should we strike with the sword?" But Jesus doesn't respond before one of them cuts the servant's ear off. (Perhaps he wasn't given enough time to reply.) Then Jesus says simply, "Stop! No more of that!" In Luke's version there's only that brief command, with no supporting reasons given. It might reflect an abhorrence of violence in general. But we might wonder why Luke's Jesus would permit his disciples to carry swords just a few verses earlier, yet forbid them to use them here in his defense.
In John's version of the arrest (18:3-11), the disciple who uses his sword is said to be Simon Peter, and the servant's name is given as Malchus. John quotes Jesus as saying to Peter, "Put your sword back into its sheath. Am I not to drink the cup that the Father has given me?" So John's focus is on the need to permit Jesus' divine mission to continue (which includes his arrest and crucifixion), not a specific opposition to violence per se.
Matthew's version of Jesus' statement is lengthier and more complex than the others (26:51-54): "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 in Matthew against the 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. But the other rationale, like John's, might be restricted to this situation only: the disciple must not interfere with Jesus' mission. (We might also wonder how the legions of angel reserves are consistent with pacifism!)
In light of this puzzling combination of texts, how did the early Christian community answer the question of whether force could ever be morally justified? Many of them seem to have constructed a dual ethic, one for Christians and another for the state. I'll use Paul, Tertullian of Carthage and Origen of Alexandria 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 to Roman Christians (ch. 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." Over a century later, Tertullian wrote (On Idolatry) that when Jesus rebuked the disciple who defended him at his arrest, he in effect disarmed every soldier. He explained to Roman rulers (Apology) that Christians believe it's better for them to be killed than to kill. And he stipulated (On the Crown) that when soldiers convert to Christianity, they must leave the military. Origen claimed that Jesus prohibited homicide, so Christians may never kill or use violence for any reason (Against Celsus; Commentary on Matthew 26:47ff.).
But all three of those early Christians, in spite of their apparently pacifist stances, 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 rulers 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." (Luther would echo Paul's words many centuries later.) Tertullian said (Apology), "We [Christians] pray ... for security to the empire; for protection to the imperial house; for brave armies...." And Origen 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 ... that whatever is opposed to those who act righteously may be destroyed" (Against Celsus).
Now 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 it's important to recognize that these authors-and possibly most early Christians-thought strict pacifism to be the only acceptable ethic for followers of Jesus.
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 could now be obligated to defend the empire with force (Demonstration of the Gospel). Ambrose, another important bishop of that era, thought that Christian love entailed a duty to use force to defend innocent third parties (Duties of the Clergy). 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, who was apparently influenced by Ambrose in many ways, recognized that Jesus had taught things that seemed to entail strict nonviolence. But like Ambrose he believed that they applied to dispositions rather than to 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, believing it to be consistent with a benevolent desire of the Church to correct its wayward children. (Letter to Publicola; Against Faustus; Letter to Marcellinus; Letter to Vincentius)
However, Ambrose (Duties of the Clergy) and Augustine (Letter to Boniface) 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. 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, he would have to do penance for the killing, often by fasting and prayer for a year or more (Verkamp).
We can also see Christian roots of the modern principle of noncombatant immunity develop in the medieval period, when secular military ideals of chivalry combined with Christian decrees of protection for clergy, peasants, women, and others who usually did not take part in combat (Johnson). Thomas Aquinas added another important ethical consideration in stipulating that Christians may only use the minimal force needed to save lives from unjust attack, an early version of the principle of proportionality.
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.
(The glorification of Peter here is rather ironic, in that Jesus rebuked him for using his sword! But the poem no doubt stirred its audience to imagine that if they had been with Jesus at his arrest, they might have hoped to have the disciple's courage and sense of moral outrage.)
Now by themselves, military courage and honor might help to reinforce limits on war conduct, e.g., in protecting noncombatants. But many of the traditional restraints on war advocated by the Church started to erode in the medieval period. In the ninth century the Vatican declared that death in battle could be spiritually beneficial for Christian soldiers: their sins could be erased if they died in defense of the Church, and they would be guaranteed entry into heaven (Halsall).
In the year 1095, Pope Urban II launched what later came to be called the First Crusade, urging European leaders to rescue the Holy Land from its Muslim occupiers. The Pope referred to Muslims as a "vile race," an "unclean nation" that had polluted Christian holy places, and called for their destruction. Killing Muslims became in effect a way for Christians to obtain 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. Even Jews in Germany were massacred by crusaders on their way to Palestine. (Halsall) Thus, ironically and tragically, a religion that began with the largely nonviolent teachings and example of Jesus evolved in its first millennium to the point where Christians were waging total, indiscriminate war against heretics and infidels.
In the wake of a series of devastating wars in Europe between Catholics and Protestants, some Christians like Francisco de Vitoria concluded that mere difference of religion should no longer be considered just cause for war. Most Christians today would find total war morally repugnant, of course, especially if waged in the name of God. Some even continue in the ancient path of pacifism in obedience to Jesus' sayings on love of enemies and non-retaliation against evil. But total holy war against infidels also remains a continuing temptation for Christian authorities.
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 and sincerely 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).
Those ideas taken in isolation might tend to preclude holy war, and perhaps even ground some form of pacifism. Indeed, the Prophet Muhammad was said to have practiced non-violence during the first 12 years of his prophetic career, even in the face of serious persecution by polytheists in Mecca (Kelsay; Hashmi). The Prophet's stance during that early Meccan period eventually served as the model for a nonviolent Islamic movement in 20th-century Afghanistan led by Abdul Ghaffar Khan, a friend and admirer of Gandhi (Easwaran).
But after the Prophet's escape to Medina in 622, he came to believe that God permitted and commanded the use of force in defense of his growing religious community. Qur'an 22:39-40 (Firestone) says, "Permission is given to those who fight because they have been wronged ... unjustly expelled from their homes only because they say, 'Our Lord is Allah." Like the Hebrew Bible, the Qur'an mandates capital punishment for certain offenses, though it also urges mercy and forgiveness in other cases. Muhammad often urged diplomacy rather than war to resolve disputes (Hashmi).
But some scholars believe that particular verses in the Qur'an (9:5 and 73) and other sayings of the Prophet go beyond defensive and retributive uses of force to permit offensive jihad to expand the territory of Islam. 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).
So 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. Muhammad himself was said to condemn Muslims to death if they abandoned their faith. Some of the early Muslim raids out of Medina against trading caravans would be hard to interpret as strictly defensive. And although Islam spread to some parts of the world like Indonesia 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 establish some important moral rules for fighting holy wars: women, children and the elderly were not to be intentionally killed, though they could be enslaved. Monks, nuns and the disabled were also to be spared from execution after a battle. (Peters) Muslim military leaders were able to draw upon some pre-Islamic principles of Arab chivalry against killing defenseless people (Hashmi). In other words, Islamic holy wars were never supposed to be total wars involving indiscriminate killing and scorched-earth tactics (Kelsay), in spite of what the leaders of Al Qaeda, Hamas or Hizbollah might say to the contrary.
On the other hand, Muslim leaders were explicitly permitted by Muhammad to kill all captured soldiers, and most adult male civilians if they were polytheists, or even if they were Jews or Christians but had fought instead of paying the poll tax. So Islam traditionally did not uphold a comprehensive principle of noncombatant immunity. Also, if civilians were likely to be killed in attacks on military areas, Muslim ethics permitted that as regrettable but necessary "collateral damage"--in fact, the moral blame rested entirely on the enemy leaders for putting their citizens in harm's way (Peters; Kelsay; Hashmi).
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 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, though some will not be acceptable to strict pacifists:
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, or while they are combatants in war.
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.
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. Even then, harms to enemy civilians should be minimized.
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 largely reflect principles that arose in the Western just-war tradition, many of which have 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).
The works of ancient Christian writers Tertullian, Origen, Eusebius, Ambrose and Augustine are available online at http://www.newadvent.org/fathers/.
Roland Bainton, Christian Attitudes toward War and Peace (1960).
Michael Broyde, "Fighting the War and the Peace: Battlefield Ethics, Peace Talks, Treaties, and Pacifism in the Jewish Tradition," in J. Patout Burns, ed., War and Its Discontents (1996).
Eknath Easwaran, Nonviolent Soldier of Islam (1999).
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, An Introduction to Buddhist Ethics (2000).
Sohail Hashmi, "Interpreting the Islamic Ethics of War and Peace," in Terry Nardin, ed., The Ethics of War and Peace: Religious and Secular Perspectives (1996).
Israeli Defense Forces, Code of Ethics, http://www.us-israel.org/jsource/Society_&_Culture/IDF_ethics.html. James Turner Johnson, The Holy War Idea in Western and Islamic Traditions (1997).
John Kelsay, Islam and War (1993).
Klaus Klostermaier, "Himsa and Ahimsa Traditions in Hinduism," in Harvey Dyck, ed., The Pacifist Impulse in Historical Perspective (1996).
The New Oxford Annotated Bible: New Revised English Bible with the Apocrypha (2001).
Rudolph Peters, Jihad in Classical and Modern Islam (1996).
Louis Swift, The Early Fathers on War and Military Service (1983).
U.S. Army Field Manual #27-10, The Law of Land Warfare, edited by Nile Stanton, http://nile.ed.umuc.edu/~nstanton/FM27-10.htm. Bernard Verkamp, The Moral Treatment of Returning Warriors in Early Medieval and Modern Times (1993).
Francisco de Vitoria, On the Law of War (1539).
Richard Wrangham and Dale Peterson, Demonic Males: Apes and the Origins of Human Violence (1996).