Article 388 of Jaafari Personal Status Law

An apostate is a person who has departed from Islam and chosen unbelief, and is of two categories: The first category: the innate apostate: a person one or both of whose parents were Muslim at the time of his conception, who then professed Islam after reaching puberty and subsequently departed from it. The second category: the religious apostate: a person whose parents were unbelievers at the time of his conception, who then professed unbelief after puberty and thus became an original unbeliever, then embraced Islam, and then returned to unbelief.