A look at the primary guidance for war in Islam—the instructions received from God by Muhammad—reveals several things: war is not meant to be the primary means for pursuing goals; it is the last resort. “The tradition of Sharia reasoning already provides an equivalent to the just-war criteria of legitimate authority, just cause, righteous intention, and (at least) ‘timely’ resort”.
There are also criteria for fighting the war, such as the forbidding of “cheating, treachery, mutilation, and the killing of children,” writes Kelsay. This, Kelsay says, is also analogous to the just war tradition. So, an eighth-century Muslim theologian specifically cited Muhammad’s injunction to always spare women, children, and old men.
Then we come to the question of who is entitled to declare jihad. At the least, it is Sunni clerics who are authorized to do that. In the case of violent Islamist movements raging around the world (including Al Qaeda), virtually not a single one has been blessed by a renowned cleric having legitimacy. And then, even when jihad is carried out, it can’t be done in the spirit of blind hatred, which the Qur’an forbids: “Let not hatred of a people cause you to be unjust” (5:8). In contrast, a person should “repel the evil deed with one which is better, then verily he, between whom and thee there was enmity (will become) as though he were a bosom friend” (41:34). “Traditionally, even external jihad has been associated in the Muslim mind with magnanimity, generosity and detachment, with all the virtues associated with chivalry,” asserts Nasr. Such qualities can be seen in Muslim warriors down the ages, he says, starting from Saladin all the way down to Ahmad Shah Masud.
Jihad is meant to be only in self-defense. The Qur’an does speak about fighting one’s enemies, as would be expected in a time of strife, but says that Muslims should battle their foes “except those who seek refuge with people between whom and you there is a covenant, or (those who) come unto you because their hearts forbid them to make war on you. . . . So, if they hold aloof from you and wage not war against you and offer you peace, God alloweth you no way against then” (4:90). And the Qur’an offers forgiveness. “Whoso foregoes [revenge] it shall be expiation for him” (5:45). And the moment the enemy ceases fighting, so should you: “If they desist, then let there be no hostility” (2:192).
And then there are the rules under which jihad or wars have to be fought. Certainly, no innocent life can be taken. Women and children and animals and trees are explicitly ruled out. Muhammad’s generous behavior on reentering Mecca is a role model for Muslims, as is Caliph Umar’s magnanimity toward Christians on conquering Jerusalem. Of course, Nasr says, a number of Muslims are violating such precepts. “But it is essential here not only for Western observers but also for many Muslims who, having lost hope, have fallen into despair and commit desperate acts to remember what the teachings of Islam as a religion are on these matters".