In Islam, Shirk () is a sin often roughly translated as "idolatry" or "polytheism", but more accurately meaning "partnerism or association [with God]". It refers to accepting other divinities or powers alongside God as associates. In contrast, Islam teaches that God does not share divine attributes with anyone, as it is disallowed according to the Islamic doctrine of tawhid. The Quran—the central religious text of Islam—states in Surah an-Nisa, that God will not forgive shirk if one dies without repenting of it.
The one who commits shirk is called a mushrik. The opposite of shirk is tawhid and the opposite of mushrik is muwahhid.
Etymology
The word shirk comes from the Arabic root sh-r-k (), with the general meaning of "to share". In the context of the Quran, the particular sense of "sharing as an equal partner" is usually understood, so that polytheism means "attributing a partner to God". In the Quran, shirk and the related word mushrikūn ()—those who commit shirk and plot against Islam—often refer to the enemies of Islam (as in al-Tawbah verses 9:1–15), though there is no equal in the English language.
Quran
According to the Encyclopaedia of Islam (2nd edition), the Quran states twice in an-Nisa verses 48 and 116 that God can forgive all sins save one: shirk.
Islamic commentators on the Quran have emphasized that a number of pre-Islamic Arabian deities and jinn, most notably the three goddesses Manat, al-Lat, and al-Uzza mentioned in the surah an-Najm, were considered associates of God.
Entities worshipped besides God are called shurakāʾ (). After Judgement Day, they will be cast into Jahannam (Hell) along with devils (fallen angels) and evil jinn, The Quranic verse al-Ma'idah 5:73 ("Certainly they disbelieve [kafara] who say: God is the third of three"), among other verses, has been traditionally understood in Islam as rejection of the Christian Trinity doctrine, but modern scholarship has suggested alternative interpretations.