Riddah (apostasy) in Islam
A murtadd (apostate) is the one who has gone out of Islam and become a kaafir (disbeliever) by his words or actions such as associating others with Allaah or prostrating to an idol, or by his giving up (some obligatory duty) or his beliefs. The apostate (disbeliever by choice) is worse than one who is a kaafir in the first place.
Jabir ibn `Abdullah narrated that a Bedouin pledged allegiance to Prophet Muhammad (SAW) for Islam (i.e. accepted Islam) and then the Bedouin got fever whereupon he said to the Prophet "cancel my pledge." But the Prophet refused. He (the Bedouin) came to him (again) saying, "Cancel my pledge." But the Prophet refused. Then he (the Bedouin) left (Medina). The Prophet said, "Madinah is like a pair of bellows (furnace): it expels its impurities and brightens and clear its good."
It was narrated that Tameem al-Daari said: “I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: "This matter (i.e., Islam) will certainly reach everywhere that night and day reach, and Allaah will not leave any house or tent [i.e., all dwellings, in towns and in the desert], but Allaah will cause this religion to enter it, and some people will be honoured because of it [by converting] and others will be humiliated because of it [for refusing to embrace it]." [Ahmad, #16344 Al-Silsilah al-Saheehah].
If a Muslim apostatizes and meets the conditions of apostasy – i.e., he is of sound mind, an adult and does that of his own free will – then his blood may be shed with impunity and he is not to not be washed (after death, in preparation for burial), the funeral prayer is not to be offered for him and he is not to be buried with the Muslims.The evidence that the apostate is to be executed is the words of the Prophet (peace and blessings of Allaah be upon him):
“Whoever changes his religion, execute him.” [Al-Bukhaari, 2794].
If it is proven for certain that a person is an apostate, and he is a friend, then he is to be treated in the following manner:
1. It is obligatory to disavow whatever he believes in of kufr and apostasy.
2. It is haraam to regard him as a friend and love him.
3. It is obligatory to advise him and call him to come back to Allah, may He be exalted.
4. He should be shunned and cut off if he persists in his misguidance, especially if there is an interest to be served by shunning him, such as exposing his evil or to discourage the other friends from following him.
Al-Bukhaari (6484) and Muslim (1676) narrated that ‘Abd-Allaah ibn Mas’ood said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “It is not permissible to shed the blood of a Muslim who bears witness that there is no god except Allaah and that I am the Messenger of Allaah, except in one of three cases: a soul for a soul (i.e., in the case of murder); a previously-married person who commits zina; and one WHO LEAVES HIS RELIGION.”
The general meaning of these ahaadeeth indicates that it is essential to put the apostate to death whether he is waging war on Islam (muhaarib) or not.