Apostasy in Islam (Arabic: ارتداد, irtidād or ridda) is commonly defined in Islam as the rejection in word or deed of their former religion (apostasy) by a person who was previously a follower of Islam. Islamic scholarship differs on the earthly punishment for apostasy, ranging from death to no punishment at all.[1]
From a Wikipedia article:
"Many medieval Sunni schools of Islamic jurisprudence held that apostasy by a male Muslim is punishable by death, differing only on whether to execute the apostate immediately or grant the apostate an opportunity to repent and thus avoid penalty. They also differed on the punishment of a female apostate: death or imprisonment until repentance,[2] these judgements are still adopted by extremist Islamic Scholars today."
Those who face death or imprisonment for turning away from their religion are unlikely to do so.