The discussion of freedom in Islam is a very long one requiring many volumes dealing with the different freedoms conferred by Islam. It will become clear to the reader that the freedom provided for by Islam is one hundred per cent so, whereas the freedom provided for in the so called free world is ten per cent or less than that.
The Limits of Freedom
Islam has given to mankind freedom of thought, freedom of speech, and freedom of action but within a correct and reasonable framework, (i.e. whereby one does not harm others or oneself), so that certain foods and drinks, which are very harmful, are not permissible because of the harm they cause to oneself. Likewise slander and assault and the like are not permissible because of the harm they cause to others. In the same way, the overuse of natural resources is not allowed because it causes harm to forthcoming generations.
The Emissary of Allah (Peace be upon him) limited every thought, word and deed through the concept of non-harming when he said:
‘There should be no harming or accepting harm in Islam.’ in the case of Samra:
‘Samra Ibn Jondab had a date palm within the confines of a garden of one of the Ansaar whose house was in the middle of the garden. Samra used to pass by the house on the way to his palm without asking permission. So the Ansaari told him to ask permission when he came but Samra refused. When this happened, the Ansaari went and complained to the Emissary of Allah who said to Samra: “If you wish to enter then seek permission” But he refused. Then the Emissary of Allah bargained with him to reach an agreeable price but he refused to sell. So he said (peace be upon him):”You will have for it a date palm in heaven” but he still refused. So the Emissary of Allah said to the Ansari: “Go and uproot it and throw it to him because there should be no harm or accepting harm.”
In another rendition related by Zararah from Abu Ja’far the Emissary of Allah said to the Ansaari “you are a man harmed and there should be no harm upon a believer” Then he gave his command so it was uprooted and thrown to him and the Emissary of Allah said to him: “go and plant it wherever you wish“.
Texts about Freedom
The discussion of freedom in the Qur’an, and in the traditions, and in Islamic jurisprudence occurs very frequently.
Allah states in the Qur’an:
‘ . . then (Oh Muhammad) remind, for you are one to remind, you are not their overlord.’ 
‘ . . . and you are not one to overawe them by force.’ 
‘ . . . and releases them from the burdens and the yokes that were upon them.’ 
‘There is no compulsion in religion, truth stands out clearly from error.’ 
‘ . . . to you your religion and to me mine.’ 
In a tradition related from Imam Amir-ol-Mo’meneen Ali Ibn Abi Talib:
‘Do not be a slave to another when Allah has made you free.’
In a well known line of poetry of Imam Hussein at Karbala:
‘Oh that I may not be killed but as a free man, even though I see death as a thing repulsive.’
Imam Hussein also said to Hurr Ibn Yazid al-Riyahiyy:
‘Your mother did not err when she named you Hurr (free) for you are free in this world and felicitous in the next.’
Islam would expect the one who does not believe in the absolute freedom in the hereafter to be free in this world.
Imam Hussein also said to those who came to fight him:
‘If you do not have a religion and don’t fear the next life then at least be free in this life.’
Ali Ibn Abi Talib used to say: “People are all free except one who, consciously, has admitted to being a slave -male or female- or he who has been proven to be a slave, whether as a youngster or an adult.’
(In a judgement) Imam Ali peace be upon him ruled that: ‘people are all free except he who, as an adult, has admitted to being someone else’s slave or proven to be so.’
Freedom for other Religions
In traditions frequently related we see that Islam adopts for every people of religion that which they themselves follow, thereby confirming their freedom in their religion. For example Imam Sadiq was asked about rulings’ (concerning everyday issues) and he replied, “what every people of religion permit is permissible”. In another tradition Imam Redha said: ‘adopt for them what they themselves adopt.’ Related from Imam al-Sadiq (Peace be upon him) that he said: ‘Whatever people profess as a matter of religion will become obligatory as a law upon them.’
Hence we see that Islam does not raise objections that the Magian or similar marries his mother or sister because that is permissible in his religion, even though his religion is in reality false. This because Islam does not seek compulsion, because of the well-known principle ‘compulsion does not last’, but rather seeks to give freedom to every individual in the matter of acting according to his beliefs. Islam would rather confront him with a logical discussion. Hence we see in the Qur’an the words:
‘Invite to the way of your Lord with wisdom and fine preaching and argue with them in the ways that are the best.’ 
It is related in many traditions that ‘the Magians inherit according to their creed, and that every people have their own marriage customs.’
Al-Koleini related, “A man insulted a Magian in front of Imam al-Sadiq who rebuked him. The man said ‘but he marries his mother and sister‘ so al-Sadiq said ‘that is the way of marriage in their religion.’” In another incident a man cursed a Magian in the presence of al-Sadiq (Peace be upon him) who scolded him and forbade him. The man then said ‘he has married his mother’ so al-Sadiq said ‘did you not know that that is the way of marriage in their religion?’ Al-Sadiq says in another tradition: ‘It is not right or proper that a Muslim slanders a Jew or a Christian or a Magian in matters where he has no knowledge.‘ He also said ‘The easiest thing to happen in this case is that he will be a liar.’ In another tradition from Al-Sadiq is that he said to one of his followers: ‘what has the object of your slander done? He is the son of the bad woman (whore). So Al-Sadiq gave him a hard stare so the man said he is a Magian who has married his sister. Imam Sadiq said; ‘Is that not the way of marriage in their religion?’
There is no compulsion in confessions
We also see that in Islamic law the ruler has no right to compel anyone to confess or even to speak.
Ibn Shahr Ashoob has related in Al-Manaqib: ‘that ‘Omeir Ibn Wai’l Al-Thaqafi was ordered by Handhala Ibn Abi Sufyan to make a claim against ‘Ali (Peace be upon him) of eighty measures of gold deposited with the Emissary of Allah who subsequently migrated from Mecca and that ‘Ali was his agent, and that if ‘Ali asked for the evidence of witnesses then the Quraysh would bear witness against him. So he came and made a claim against ‘Ali who assayed all the deposits and saw the names of their owners upon them and found no trace of what ‘Omeir had mentioned. So ‘Ali counselled him at length but he said ‘there are those who will testify to this namely Abu Jahl, ‘Akrama, ‘Aqabah Ibn Abi Mo’it, Abu Sufyan and Handhala.’ ‘Ali said ‘this is a ploy which will backfire on whoever planned it.’ Then he ordered the witnesses to sit in the Ka’bah and said to ‘Omeir: ‘tell me now when was it that you deposited your sum with the Emissary of Allah, what time of day was it?’ He said ‘the midmorning and he took it in his hand and gave it to his servant.’ Then ‘Ali summoned Abu Jahl and asked him the same question. He said: ‘I don’t have to say that.’ Then he summoned Abu Sufyan and asked him and he said: ‘he (‘Umeir) paid it at sunset and he (the Prophet) took it from him and put it in his sleeve. Then he summoned Handhala and asked him about that and he said: ‘it was when the sun reached its zenith and he (the Prophet) kept it in his hand until he left. Then ‘Ali summoned ‘Aqaba and asked him. He said: ‘he received it in his hand and put it immediately in his house and this was in the afternoon.’ Then he summoned ‘Akrama and asked him. He said:’ It was at dawn, he took it and put it at once in Fatima’s house.’ Then ‘Ali turned to ‘Omeir and said: ‘I see your face has yellowed and your condition has changed.’ ‘Omeir said;’ I will tell the truth, I did not have a deposit with the Emissary of Allah but they forced me to say so.’
(imamshirazi.com / 17.04.2011)