There has been differences of opinion on the English lexical meaning of “apostasy” and apostate” as well as the Arabic equivalents. We will use the English words on the bases given by their definitions in Webster’s, together with the Arabic lexical and legal definitions for the words “murtadd” and “irtidad”.
From Webster’s New World Dictionary & Thesaurus:
apostate: a-pos-tate n. a person guilty of apostasy; renegade adj. guilty of apostasy n. — Syn. renegade, one of little faith, backslider, defector; see deserter, traitor. See heretic, heretical, impious, rebel, recreant, scab, skeptic, turncoat
apostasy: a-pos-ta-sy n., pl. -sies an abandoning of what one has believed in, as a faith, cause, or principles See defection, desertion, disloyalty, heresy
Are the semantic equivalents of apostate and apostasy also found in the Arabic words murtadd and irtidad which respectively correspond to them?
The words apostate and apostasy can be equally translated into Arabic respectively as kafir or murtadd, and as kufr or irtidad.
The Arabic word murtadd applies to a Muslim who publicly declares kufr or unbelief — we seek refuge in Allah — by so stating or by denying a fundamental tenet of creed — such as Allah’s angels — or definitely abandoning or denying a fundamental obligation in the Religion such as prayer (salaat), or acting in a way unmistakably tantamount to unbelief such as prostrating to an idol.
The Law considers irtidad not an exercise of personal freedom — as the West construes atheism and “agnosticism” in its own societies — but a crime and declaration of war against Muslim society, which is duty-bound to protect itself from its consequences. This is a condition of irtidad as established by the Prophet’s statement — Allah bless and greet him:
“The blood of a Muslim is illicit to shed except for one of three reasons: a married adulterer must be stoned; one who wilfully commits murder must be put to death; and a man who comes out of Islam and fights Allah and His Prophet must be put to death or crucified or banished from the earth.”
It is narrated with transmission chains of trustworthy narrators from `A’isha by al-Nasa’i and Abu Dawud in their Sunan and al-Bayhaqi in al-Sunan al-Kubra. This hadith explicitly makes “fighting Allah and His Prophet,” i.e. fighting Islam and Muslims, a condition sine qua non for punishability by death. For then the murtadd becomes the same as an enemy soldier in wartime (muharab), i.e. an enemy of Islam on the battlefield.
As for one who professes and observes Islam but harbours unbelief without publicly declaring it is not a murtadd, but a munafiq or dissimulator.
The munafiq is not a kafir in the eyes of the Law and must be treated as a Muslim up to and including burial rites and inheritance status, while the murtadd is a kafir in the eyes of the Law and is subject to the penal law (hadd) that applies to the murtadd as enforced only by the Islamic state.
It is forbidden for individuals to enforce any penal law or act of war whatsoever whether in the presence or in the absence of an Islamic state except by lawful mandate, but the latter can be de facto, as in the case of a people’s legitimate defense against aggression.
One who professes Islam without observing its obligations and prohibitions nor harboring unbelief is neither a murtadd nor a munafiq nor a kafir but a fasiq or depraved person — may Allah guide us and you.