In the Qur'an, God's plan for humankind is not that everyone should follow the same path; instead, belief is left to individual conscience and personal reflection, and should be sincere. From the perspective of the Qur'an, forcing belief on another does not result in genuine belief, which is an essential element of faith. The Qur'an therefore condemns hypocrisy and hypocrites in many verses, and exhorts sincerity (9:68; 63:1). It also condemns attitudes that promote blind imitation of ancestral precedents at the expense of independent thought and personal conviction (2:170). The Qur'an declares: "Had God willed it, He would have guided all to the right path" (see 10:99; 13:31; 16:9). Furthermore, on the Day of Judgment individuals will stand before God and be questioned about what they did or failed to do (10:41). Accountability is thus very closely connected to the individual and the personal responsibility to choose (4:115; 72:23).
For the Qur'an, revealed religion is sacred and each scripture must be approached with respect. Both Judaism and Christianity, for example, are respected as "religions of the book" alongside Islam (5:69; 3:113-114). The same degree of respect, however, is not shown to belief-systems that involve practices such as idol worship, which were widespread in Arabia at the time of revelation: these beliefs and practices are not recognized as legitimate by the Qur'an. Despite this, the Qur'an urges Muslims to deal with all people - including idolaters - with respect, as long as they too show respect (49:11). The Qur'an also strongly rejects the idea of forcing anyone to adopt Islam, or of initiating hostilities toward any non-Muslim communities with whom Muslims had peaceful relations (9:4). As such, the Qur'an reflected a remarkable degree of tolerance towards other religions (5:69) at a time when religious tolerance was not generally the norm.
There is little disagreement among Muslim scholars on the legitimacy of conversion from one faith to another outside Islam. However, conversion of an individual from Islam to another religion has been consistently banned, and severe punishment applied as a deterrent. The question remains as to the extent to which the prohibition on conversion from Islam and its punishment are based on clear Qur'anic and prophetic guidance, and whether there is room to argue for moving away from the death penalty for conversion to simply consider conversion a sin, not a punishable crime.
An examination of the Qur'an suggests that it does indeed uphold the view that individuals had the freedom to convert from Islam - if they desired - in a broad sense. The Qur'an makes it clear that individuals in Mecca were free to decide not to follow the Prophet and his teachings (17:15; 18:29; 6:104), although it criticizes those Muslims who converted from Islam: "The truth [has now come] from your Sustainer: let, then, him who wills, believe in it, and let him who wills, reject it" (18:29). Similarly, the Qur'an strongly emphasizes that individuals should not be compelled to believe in Islam: "There is no coercion in matters of faith/religion" (2:256). The Prophet's duty was to deliver the message, not to determine who should or should not believe this message (4:80; 24:54; 5:99; 64:12; 3:20; 88:21).
On a number of occasions, the Qur'an declares that those who move away from the true path of God and the Prophet are to be condemned and punished in the life after death (4:115; 72:23). However, in line with its view of individual and personal responsibility for matters of belief and religion, the Qur'an seems to allow Muslims the option to convert to their former religions or to any other religion during their lifetime (3:20; 64:12), even though it declares that this action will lead to the individual's eternal damnation. The Qur'an also deals with what appears to be apostasy in several verses; but despite condemning those individuals who had - in some cases, repeatedly - committed the sin of apostasy (63:3), the Qur'an envisaged a natural death for them, rather than capital punishment.
There is no evidence to indicate that the Prophet Muhammad himself ever imposed the death penalty on an apostate for the simple act of conversion from Islam. Such penalties were imposed by the Prophet in a number of specific cases, and were related to crimes other than apostasy. Notably, a report in the hadith collection of Bukhari (one of the most important and reliable collections of hadith for Sunni Muslims) details a man who came to Medina and converted to Islam. Shortly after his arrival, this man wanted to return to his former religion and asked the Prophet for permission to do so. The Prophet let him go without imposing the death penalty, or any other punishment.
In early Islamic history, the question of apostasy appears to have been closely associated with the security of the Muslim community, and was defined in relation to combating treachery and aggression. As I've argued elsewhere, the issue of apostasy at the time was closely related to both the identity and the survival of Muslims. Unbelief (kufr) on its own was not used in the Islamic legal tradition as a justification for war or for any form of capital punishment. Nonetheless, the Qur'an asserts it is an individual's responsibility to follow the approved path or not to follow it (27:92; 10:108).
The vast array of Qur'anic texts and the practice of the Prophet thus demonstrate that while apostasy itself is strongly discouraged, they leave the issue to the individual, respecting the right of the individual to believe or not to believe, to remain a Muslim or to leave Islam.