The word "khawarij ", that is, "rebels", comes from khuruj which means revolt and "insurrection''. This group came into being during the process of arbitration. The battle of Siffin, in its last day of fighting, was turning out in Ali's favour; Mu'awiyah, in consultation with Amr ibn al-'As, conceived a skilful stratagem. He had seen that all his pains had produced no result, and that he was only one step away from defeat. He saw that there was no way to save himself except by having recourse to the creation of confusion, so he ordered that Qur'ans should be raised up on the points of spears to show that they were people of prayer and the Qur'an, and that the Book should be used to arbitrate between the two sides. It was not the first time that this had been done, for it was the same thing that Ali had done before but which had not been accepted. Even now they had not accepted it; it was a subterfuge for them to find a way to save themselves and rescue themselves from a sure defeat.
Ali cried out: "Strike at them! They are using the pages and the paper of the Qur'an as a ruse, they want to protect themselves behind the words and writing of the Qur'an and afterwards carry on in their same old anti Qur'anic way. When opposed to its truth, the paper and binding of the Qur'an is of no value and worthy of no respect; it is I who am the reality and the true manifestation of the Qur'an. They are using the paper and the writing of the Qur'an as an excuse to destroy its truth and meaning!
A group of undiscriminating, unknowing and sanctimonious persons, who formed a sizeable proportion, gesticulate to each other. What does Ali mean? They called out:
"Should we fight against the Qur'an? Our battle is to reestablish the Qur'an, and now they have submitted to the Qur'an, so what are we fighting for?
"I also say I am fighting for the Qur'an, said Ali. "But they have no connection with the Qur'an. They have put up the words and writing of the Qur'an as a means to save their own souls.
There is a question in Islamic law, in the section on jihad, concerning the situation of unbelievers shielding themselves behind Muslims. The problem is that if the enemies of Islam put a group of Muslim prisoners of war at the front of their ranks as a shield, and they themselves are busy with their activities, ma king headway behind this front, so that if the Islamic forces try to defend themselves, or attack them and halt their advance, there is no alternative but to also eliminate, through necessity, their Muslims brothers who have become a shield; that is, if there is no possibility of access to the combating and attacking enemy apart from through the killing of Muslims, then in this situation the killing of a Muslim for the vital interests of Islam, and so as to save the lives of the rest of the Muslims, becomes permissible in Islamic law.. In fact, they too are soldiers of Islam and will have become martyrs in the way of God. However, blood money must be paid for them from the Islamic treasury to their surviving relatives. This is, of course, not only a particularity of Islamic law, but there is a quite definite law among the international rules and regulations of war and military action that if the enemy wishes to use your own forces, you can eliminate those forces so as to reach the enemy and force them back.
"If, when there are real, live Muslims, continued Ali, "and Islam says Attack!' so as to ensure a Muslim victory, then there can be no objection made to the paper and bindings of books. Respect for pages and writing is because of their meaning and contents. Today the fighting is for the contents of the Qur'an, but these people have set up the pages as a means for the destruction of the meaning and contents of the Qur`an."
However, the ignorant and uninformed drew down a black curtain in front of their minds and kept out the truth. "In addition to the fact that we will not fight with the Qur'an, they said, "we know that fighting with it is itself a sin, and we must kill so as prevent this. We will fight with those who fight against the Qur'an. Only an hour was needed to secure a victory; Malik al-Ashtar, who was a brave, devoted and unselfish officer, had thus gone out to destroy the pavillion of Mu'awiyah's command and to clear the path of Islam of obstacles. At this very moment, this group pressured Ali by saying they would attack from behind. Ali urged them not to, but they increased their protest, and, what is more, showed that they would be completely obstinate.
Ali sent a message to Malik to stop the fighting and to return from the place where the fighting was.
He sent an answer back to Ali that if he were to give his permission for a few moments more the battle would be finished, and the enemy destroyed. But the Khawarij drew their swords and threatened to hack Ali to pieces unless he called him back.
Then again word was sent to him that if he wanted to see Ali alive, he should stop the battle and come back. He returned, and the enemy were jubilant that their stratagem had proved efficacious.
The fighting stopped so that they could leave arbitration to the Qur'an. An arbitration committee was set up, and arbitrators selected from the two sides to rule on the basis of what was agreed on by both sides in the Qur'an and sunnah and to bring an end to hostilities; or else they would add another difference to the already existing differences and cause the situation to deteriorate.
Ali said that they should choose their arbitrator, and then he would detail his own. Without the slightest dispute, they unanimously chose Amr ibn al-'As, the deviser of the stratagem. Ali proposed Abdullah ibn al-'Abbas, who was versed in politics, or Malik al-Ashtar, a self-sacrificing, clear-sighted man of faith, or else someone like them. But those fools were looking for someone of their own kind, and they chose a man of the like of Abu Musa al-Ash'ari, a man of no perspicacity who was not on good terms with Ali. However much Ali and his friends sought to enlighten these people that Abu Musa was not the man for the job and that such an appointment was not suitable for him, they said that they would not agree to anyone else. Then he said that since things had got to that point,: they should do whatever they wanted. So, in the end, they chose this Abu Musa as the arbitrator from the side of Ali and his companions.
After months of consultation, Amr ibn al- As said to Abu Musa that it would be better for the interests of the Muslims if neither Ali nor Mu'awiyah were caliph, that they should choose a third one, and that there was no one else they could choose but Abdullah ibn Umar, Abu Musa's son-in-law. Abu Musa said that that was right and asked what they should do. Amr ibn al-'As said: "You should remove Ali from the caliphate, and I will do the same with Mu'awiyah. Then the Muslims will go and elect a worthy person who will surely be Abdullah ibn Umar. Thus the roots of sedition will be destroyed.
They terminated on this matter and announced that the people should gather together to listen to their conclusions.
The people assembled. Abu Musa turned towards Amr ibn al- As to stand up and announce his opinion. Amr ibn al-'As said: "Me? You are the respected, white-bearded man, a companion of the Prophet. Never would I presume such a thing as to speak before you!
Abü MUsم moved from his place to rise and speak. Now everyone's heart was beating fast, all eyes were staring, each person held his breath, waiting to see what the result had been. He started to speak: "After due deliberation on what was in the interests of the community, we saw that neither Ali nor Mu'مwiyah should be caliph. More than this it is not for us to say, for the Muslims themselves know what they wish. The he took his ring from the finger of his right hand and said : "I have removed Ali from the caliphate, just as I remove this ring from my finger.
When he had finished he stepped down. Then Amr ibn al-'As got up and said: "You have all heard the speech of Abu Musa saying that he has removed Ali from the caliphate. I too remove him from the caliphate, just as Abu Musa has done. Then he took his ring off his right hand and then put it onto his left hand, and said: "I set up Mu'awiyah in the caliphate, just as I put this ring on my finger. When he had said this he stepped down.
The meeting lapsed into commotion. The people began to attack Abu Musa, and some beat him with their whips. He fled to Mecca, and Amr ibn al-'As went to Damascus.
The Khawarij, who had brought about this sequence of events, saw the scandal of this arbitration with their own eyes, and realized their mistake. But they could not understand where exactly their error lay. They did not say that their mistake lay in falling for Mu'awiyah, and Amr ibn al-'As' scheme and bringing the war to a halt; nor did they say that after the setting up of the arbitration they had blundered in choosing their 'referee', in putting up Abu Musa as Amr ibn al - As' counterpart. No; instead they said that in putting up two human beings to arbitrate and be "referees in the matters of the religion of God they had gone against the divine law and had done an act of unbelief, for the judge is only God, not man.
Then came to Ali and said: "We did not understand. We chose a man as an arbitrator. You have become an unbeliever, and so have we. But we repent; you too should repent. Otherwise, the tragedy will be repeated.
"In any situation, said Ali, "repentance is good. We are always repenting for our sins. But they said this was not enough, and that he had to confess that arbitration was a sin, and that he repented of that sin. But he said that it had not been he that had brought about the affair of arbitration, it had been them, and that they had seen the result themselves. What was more, how could he declare as a sin something that Islam had made lawful, or confess to a sin which he had not perpetrated.
From this point on, they set to work as a religious sect. At the beginning they were a rebellious and mutinous group, and it was for that reason that they were called "Khawarij , but they gradually drew up basic beliefs for themselves and created a "party that only had a political colouring to begin with but which step by step assumed the form of a religious group, taking on a religious colouring. Afterwards the Khawarij moved into action as a vehemently propagandist group as supporters of a religious sect. They eventually got the idea that they had discovered a worldly, corrupt root in Islam, and they came to the conclusion that Uthman, Ali and Mu'awiyah were all in error and sin. They decided that they had to struggle against this corruption that had come into existence, and they gave it the name of "bidding to good and forbidding evil. Thus the Khawarij sect came into existence under this banner.
Now, "bidding to good and forbidding evil has, before anything else, two fundamental principles: one is a profound and knowledgeable insight into the religion, and the other is a profound insight into how to act. If there is no profound knowledge of religion, as we learn from ahadith (traditions), the loss that will be incurred in doing this will be greater than its benefit. And a profound insight into the correct way to act depends on two conditions which are called, in Islamic jurisprudence, ihtimalu t-ta'thir, that is, the possibility of effective action, and 'adamu tarattub-i l-mafsadatin alayh, that is, the absence of any resulting cause of evil, and this can only come about by the exercising of reason in these two duties.
The Khawarij had neither a profound knowledge of religion, nor a profound insight into prudent action; they were people of ignorance, lacking in any profound knowledge. In fact, they rejected any kind of profound knowledge of how to act, because they understood this duty to be a matter of obedience and they claimed that it should be performed blindly.
Source - Polarization around the character of Imam Ali, by Shahid Murtadha Mutahhari.
source : http://www.imamalinet.net/