Under the scheme of the divine trial of human beings, God has granted man freedom. Due to this freedom, enmities may develop between people (20:123), which sometimes lead them to war. But Islam makes a clear difference between enmity and war.
Believers do not have the right to wage wars against their enemies. What the believers have to do as regards their enemies is far from waging war. Their duty is to peacefully convey to them the message of Islam. The Quran gives a clear injunction on this subject:
“And good and evil deeds are not alike. Repel evil with good. And he who is your enemy will become your dearest friend.” (41:33-34)
That is to say, Islam believes in turning one’s enemy into a friend through peaceful means, instead of declaring him an enemy and then waging war against him.
Islam does give permission to do battle. But such permission is given only in the case of an attack by opponents in spite of the policy of avoidance being followed by the Muslims, thus creating a situation where self-defense is required. The Quran has this to say: “Permission to take up arms is hereby given to those who are attacked because they have been wronged” (22:38). At another place the Quran gives a valid reason for fighting: “They were the first to attack you” (9:13).
This shows that according to the teachings of Islam, war is to be waged not against the enemy but against the aggressor. If Muslims hold someone to be their enemy, that does not give them the right to attack him. The one and only right given to them is to convey the peaceful message of Islam. Islam permits defensive fighting against violent aggression, but only when all efforts at avoidance and reconciliation have failed. The practical example of the Prophet Muhammad PBUH provides an incontrovertible proof of the value of this policy.