Compulsion in Religion. One of the fundamental truths established by the sacred texts is that no one can be compelled to accept Islam. It is the duty of Muslims to establish the proof of Islam to the people  so that truth can be  made clear from falsehood. After that, whoever wishes to accept Islam may do so and whoever wishes to continue upon unbelief may do so. No one should be threatened or harmed in any way if he does not wish to accept Islam.

Among  the  many  decisive  pieces  of  evidence  in this  regard  are  the following. God  says,

“Let there be  no  compulsion  in  religion. Truth  has  been made clear from error. Whoever rejects false worship and believes in God has grasped the most trustworthy handhold that never breaks. And God hears and knows all things.” (Quran 2:256)

God says, “If it had been your Lord’s will, all of the people on Earth would have believed.Would you then compel the people so to have them believe?” (Quran 10:99)

God says, “So if they dispute with you, say ‘I have submitted my whole self to  God, (and  so) have those who follow me.’ And  say  to  the  People  of  the Scripture and to the unlearned,‘Do you also submit yourselves?’ If they do, then  they  are  on  right  guidance. But  if  they  turn  away,  your  duty  is  only  to convey the Message. And Allah is All-Seer of (His) slaves.” (Quran 3:20)

God says, “The Messenger’s duty is but to proclaim the Message.” (Quran 5:99)

It  is  important  to  note  that  these  last  two  verses  were  revealed  in Medina. This is significant, since it shows that the ruling they gave was not just contingent on the Muslims being in Mecca in a state of weakness.

Some  people  might  be  wondering  that  if  Islam  indeed  advocates  such  an approach,  then  what’s all  this  we  hear  about  jihad? How can  we  explain  the warfare that the Prophet, may the mercy and blessings of God be upon him, and his Companions waged against the pagans? The answer to this is that jihad in Islamic  Law can be  waged for a number of reasons, but compelling people to accept  Islam  is  simply  not  one  of  them. As  for  conversion,  this  is  to  be  done peacefully   by   disseminating   the   Message   with   the   written   and   spoken word. There is no place for the use of weapons to compel people to accept Islam.

The Prophet said in his letter to the Roman governor Heraclius, “I invite you to accept Islam. If you accept Islam, you will find safety. If you accept Islam, God will give you a double reward. However, if you turn away, upon you will be the sin of your subjects.” (Saheeh Al-Bukhari, Saheeh Muslim)

Once people have heard the Message without obstruction or hindrance and the  proof  has  been  established  upon  them,  then  the  duty  of  the Muslims  is done. Those  who  wish  to  believe  are  free  to  do  so  and  those  who  prefer  to disbelieve are likewise free to do so.

Even when the Muslims are compelled to fight and then, as a consequence, subdue the land, their duty thereafter is to establish God’s law in the land and uphold  justice  for  all people,  Muslim  and  non-Muslim. It  is  not  their  right  to coerce  their  subjects  to  accept  Islam  against  their  will.Non-Muslims  under Muslim rule must be allowed to remain on their own faith and must be allowed to practice the rights of their faith, though they will be expected to respect the laws of the land.

Had the purpose of jihad been to force the unbelievers to accept Islam, the Prophet would never have commanded the Muslims to refrain from hostilities if the  enemy  relented. He  would  not  have  prohibited  the killing  of  women  and children. However, this is exactly what he did.

During a battle, the Prophet SAW people gathered together. He dispatched a man to find out why they were gathered.The man returned and said, “They are gathered  around  a  slain  woman.” So God’s Messenger said, “She should not have been attacked!” Khalid ibn  Al-Walid was  leading  the  forces,  so he dispatched a man to him saying, “Tell Khalid not  to kill women  or laborers.”(Sunan Abi Dawud)

Therefore, even in the heat of battle against a hostile enemy, the only people who may be attacked are those who are actually participating in the fighting.

Compulsion in Religion. Had the purpose of jihad been to force the unbelievers to accept Islam, the rightly guided Caliphs would not have prohibited the killing of priests and monks who refrained from fighting. However, this is exactly what they did. When the first  Caliph, Abu Bakr, sent an army to Syria to fight the aggressive Roman legions, he went out to give them words of encouragement. He said,

“You are going to find a group of people who have devoted themselves to the worship of God (i.e. monks), so leave them to what they are doing.”

Source: Islamhouse.com