Apostasy in Islam (Arabic: ردة riddah or ارتداد irtidād) is commonly defined as the conscious abandonment of Islam by a Muslim in word or through deed. It includes the act of converting to another religion, by a person who was born in a Muslim family or who had previously accepted Islam.
The definition of apostasy from Islam and its appropriate punishment(s) are controversial, and they vary among Islamic scholars and Islamic schools of thought. Apostasy in Islam may include in its scope not only the renunciation of Islam by a Muslim and the joining of another religion or becoming non-religious, but questioning or denying any "fundamental tenet or creed" of Islam such as the divinity of God, prophethood of Muhammad, or mocking God, or worshipping one or more idols. However, Muslim jurists from the early period developed legal institutions to circumvent this harsh punishment. These institutions set the standard for what counts as apostasy from Islam so high that before the 11th century practically no judgment of apostasy could be passed. The apostate term has also been used for people of religions that trace their origins to Islam, such as the Bahá'ís in Iran, but who were never actually Muslims themselves. Apostasy in Islam does not include acts against Islam or conversion to another religion that is involuntary, forced or done as concealment out of fear of persecution or during war (Taqiyya or Kitman).
Until the late 1800s, the vast majority of Islamic scholars in Madh'hab (Sunni) and Imamah (Shia) schools of jurisprudence held that for adult men, apostasy in Islam was a crime as well as a sin, an act of treason punishable with the death penalty, typically after a waiting period to allow the apostate time to repent and return to Islam. The kind of apostasy generally deemed to be punishable by the jurists was of the political kind, although there were considerable legal differences of opinion on this matter. Wael Hallaq states that "[in] a culture whose lynchpin is religion, religious principles and religious morality, apostasy is in some way equivalent to high treason in the modern nation-state." In the late 1800s, the use of criminal penalties for apostasy fell into disuse, although civil penalties were still applied. In the late 1800s, the use of criminal penalties for apostasy fell into disuse, although civil penalties were still applied.
The majority of modern Muslim scholars continue to hold the traditional view that the death penalty for apostasy is required by the two primary sources of Sharia - the Quran and the Hadiths, while others argue that the death penalty is an inappropriate punishment, inconsistent with the Qur'anic injunctions such as Q.88:21-22 or "no compulsion in religion"; and/or that it is not a general rule but it was enacted at a time when the early Muslim community faced enemies who threatened its unity, safety, and security, and needed to prevent and punish the equivalent of desertion or treason, and should be enforced only if apostasy becomes a mechanism of public disobedience and disorder (fitna). As such moderate Muslims reject such penalty. According to critics, the death penalty or other punishment for apostasy in Islam is a violation of universal human rights, and an issue of freedom of faith and conscience. Some consider apostasy in Islam to be some form of religious crime, although others do not.