Apostasy in Islam (Arabic: ردة, romanized: ridda or ارتداد, irtidād) is commonly defined as the abandonment of Islam by a Muslim, in thought, word, or through deed. It includes not only explicit renunciations of the Islamic faith by converting to another religion or abandoning religion altogether, but also blasphemy or heresy by those who consider themselves Muslims, through any action or utterance which implies unbelief, including those who deny a "fundamental tenet or creed" of Islam. An apostate from Islam is known as a murtadd (مرتدّ).
While Islamic jurisprudence calls for the death penalty of those who refuse to repent of apostasy from Islam, what statements or acts qualify as apostasy, and whether and how they should be punished, are disputed among Muslim scholars, with liberal Islamic movements rejecting physical punishment for apostasy. The penalty of killing of apostates is in conflict with international human rights norms which provide for the freedom of religions, as demonstrated in human rights instruments such as the Universal Declaration of Human Rights, the International Covenant on Civil and Political Rights, and the International Covenant on Economic, Social and Cultural Rights provide for the freedom of religion.Until the late 19th century, the majority of Sunni and Shia jurists held the view that for adult men, apostasy from Islam was a crime as well as a sin, punishable by the death penalty, but with a number of options for leniency (such as a waiting period to allow time for repentance or enforcement only in cases involving politics), depending on the era, the legal standards and the school of law. In the late 19th century, the use of legal criminal penalties for apostasy fell into disuse, although civil penalties were still applied.
