3-Freedom of Religion.
The Faith of Islam is founded upon liberal and tolerant principles, and another manifestation of its tolerance is that it guarantees the freedom of religion and the freedom of belief.
With the establishment of the Faith of Islam, it ordained three principles concerning the freedom of religion and the freedom of belief.
The first principle was that no one was to be forced to renounce his religion and to conform to Islam. This is expressed in the following Quranic verse "Let there be no compulsion in religion : Truth stands out clear from Error" 
The Muslims adhered to this principle in their wars with their enemies who followed different faiths and they granted the nations that they conquered freedom of religious belief. They paid taxes and obeyed the ruler of the Muslim state, in return for the state's defence of them against any attack. Their religion, religious rites, houses of worship - churches or synagogues - were regarded with respect and safeguarded against any harm. After Jerusalem surrendered, `Umar bn Al Khattab said to its people "Omar grants the people of this land protection and security for them, for their churches and their crosses. None of them is to be forced to renounce his religion or is to be harmed".
The second principle ordained by the Faith of Islam is the freedom of religious debate. God Almighty advises the Muslims to adhere to logic and reason in their discussions with people of other religions. Muslims are to base their discussions upon convincing those who listen to them by presenting proof and evidence to support their argument. In the following Quranic verse, God Almighty addresses the Prophet Muhammad, blessings and peace be upon him : "Invite (all) to the Way of thy Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most gracious : . .."God addresses the Muslims in the following Quranic verse : "And dispute ye not with the People of the Book, except with means better (than mere disputation) " God Almighty also adresses people of other faiths in the following Quranic verses Say : "Produce your proof if ye are truthful''"Have ye any (certain) knowledge ? If so, produce it before us . . .
"Say : "Do ye see what it is ye invoke besides God? Show me what it is they have created on earth, or have they a share in the heavens? Bring me a Book (revealed) before this, or any remnant of knowledge (ye may have), if ye are telling the truth ! "
The Caliphs of the Abbassid Dynasty held meetings in which they discussed religious matters and many scholars who adhered to various religious sects, schools of jurisprudence and different faiths attended these religious debates. They discussed issues on belief and the various creeds, and made comparisons between religions. Each one of them declared his opinion in complete frankness without the slightest apprehension of being reprimanded. The Caliphs did not only tolerate these discussions, but they actually encouraged them and personally participated in them.
The third principle established by Islam is that true faith is the result of one's indisputable and absolute conviction concerning one's belief and not the result of blind imitation. Islam accordingly abolished the principles upon which people had previously based their adherence to their faiths before the advent of Islam. These principles had been based upon blind imitation without conviction, and the Faith of Islam encourages people to base their faith and belief on their personal conviction and to spread their faith by sound proof and logic. Islam urges people to ponder and meditate and to refuse what is not supported by proof and evidence. Many scholars of religion declared that faith which is based upon blind imitation is not true faith. God Almighty condemned the infidels for their blind imitation of their forefathers' religion and for refusing to ponder and meditate on the divine Truth. This is mentioned in the following Quranic verses : "When it is said to them : "Follow what God hath revealed" they say : "Nay, We shall follow the ways of our fathers". What even though their fathers were void of wisdom and guidance ?"
"And when it is said to them "Come to what God hath revealed ; come to the Apostle" they say `Enough for us are the ways we found our fathers following'. What even though their fathers were void of knowledge and guidance ?" 
Sheikh Muhammad Abdu said that he who adheres to blind imitation in his faith without conviction or reasoning is in the same category as infidels. In fact a person is not a true believer unless he understands his religion and is convinced by it. He who is accustomed to believing without convinction or reasoning and performs deeds - even if they are righteous - without comprehension, is not a true believer in the Faith.
Belief and faith in one's religion is not meant to harness man to goodness as animals are harnessed to their labour, but to promote his reasoning and his soul by knowledge, so that he would perform good deeds because he would understand that they are good and righteous and approved by God Almighty. He would also abstain from sin because he would understand its sinful consequences and the extent of its evil.
 Surah II, verse 256
 Surah XVI, verse 125.
 Surah XXIX, verse 46.
 Surah II, verse 111.
 Surah VI, verse 148.
 Surah XLVI, verse 4.
 Surah II, verse 170.
 Surah V, verse 104.