In Islam, Shirk () is a sin often roughly translated as "idolatry" or "polytheism", but more accurately meaning "partnerism or association [with God]".Nonbelief: An Islamic Perspective 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.Kamoonpuri, S: "Basic Beliefs of Islam" pages 42–58. Tanzania Printers Limited, 2001. 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.Cenap Çakmak. Islam: A Worldwide Encyclopedia. ABC-CLIO 2017. p. 1450.

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".A. A. Nadwi, "Vocabulary of the Quran" 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.Encyclopaedia of Islam, volume 9, 2nd edition, s.v. 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.Pantić, Nikola. Sufism in Ottoman Damascus: Religion, Magic, and the Eighteenth-century Networks of the Holy. Taylor & Francis, 2023. chapter 3

Entities worshipped besides God are called shurakāʾ ().Magic and Divination in Early Islam. (2021). Vereinigtes Königreich: Taylor & Francis.Eichler, Paul Arno, 1889-Publication date 1928 Topics Koran Publisher Leipzig: Klein Collection microfilm; additional_collections Digitizing sponsor Internet Archive Contributor Internet Archive Language German After Judgement Day, they will be cast into Jahannam (Hell) along with devils (fallen angels) and evil jinn, to whom the polytheists are said to sacrifice in order to gain protection.

Charles Adams writes that the Quran reproaches the People of the Book with kufr for rejecting Muhammad's message when they should have been the first to accept it as possessors of earlier revelations, and singles out Christians for disregarding the evidence of God's unity. 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. Other Quranic verses strongly deny the divinity of Jesus, the son of Mary, and reproach the people who treat Jesus as equal with God as disbelievers, who will be doomed to eternal punishment in Hell.Joseph, Jojo, Qur’an-Gospel Convergence: The Qur’an’s Message To Christians , Journal of Dharma, 1 (January–March 2010), pp. 55-76Mazuz, Haggai (2012) Christians in the Qurʾān: Some Insights Derived from the Classical Exegetic Approach, Journal of Dharma 35, 1 (January–March 2010), 55-76 The Quran also does not recognise the attribute of Jesus as the Son of God or God himself but respects Jesus as a prophet and messenger of God, who was sent to children of Israel.Schirrmacher, Christine, The Islamic view of Christians: Qur’an and Hadith, https://www.worldevangelicals.org

Some Muslim thinkers, such as Mohamed Talbi, have viewed the most extreme Quranic presentations of the dogmas of the Trinity and divinity of Jesus (al-Ma'idah 5:19, 5:75-76, 5:119) as non-Christian formulas, which were rejected by the Christian Church, as well.

Cyril Glasse criticises the use of kafirun ( kafir) to describe Christians as a "loose usage". According to the Encyclopaedia of Islam, traditional Islamic jurisprudence has ahl al-kitab being "usually regarded more leniently than other kuffar (pl. of kafir)," and "in theory," a Muslim commits a punishable offense if he says to a Jew or a Christian: "Thou unbeliever."

Historically, People of the Book permanently residing under Islamic rule were entitled to a special status known as dhimmi, and those who were visiting Muslim lands received a different status known as musta'min. In the Quran, Jews and Christians—though accused of believing in shared divinity by asserting lineage between God and Ezra or Jesus, respectively—are not described as mushrik.Gimaret, D., “Tawḥīd”, in: Encyclopaedia of Islam, Second Edition, Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Consulted online on 25 February 2024 First published online: 2012 First print edition: , 1960-2007 The term is reserved for pre-Islamic beliefs that associated partners with God. Nonetheless, medieval Muslim philosophers identified belief in the Trinity with shirk ("associationism"), by limiting the infinity of God by associating his divinity with physical existence.Learning from other faiths Hermann Häring, Janet Martin Soskice, Felix Wilfred - 2003 - 141 "Medieval Jewish (as well as Muslim) philosophers identified belief in the Trinity with the heresy of shituf (Hebrew) or shirk (Arabic): 'associationism', or limiting the infinity of Allah by associating his divinity with creaturely being"

Theological interpretation In a theological context, one commits shirk by associating some lesser being with God (Allah). The sin is committed if one imagines that there is another power associated with Allah as a partner.Mark, Durie. "Semantic decomposition of four Quranic words." Russian Journal of Linguistics 26.4 (2022): 937-969. It is stated in the Quran:"Allah forgives not that partners should be set up with Him, but He forgives anything else, to whom He pleases, to set up partners with Allah is to devise a sin most heinous indeed"—Quran, an-Nisa, 4:48Faruki, Kemal. "TAWḤĪD AND THE DOCTRINE OF'IṢMAH." Islamic Studies 4.1 (1965): 31-43.

The term is often translated as polytheism, but it is more complex than that.Mulia, Siti Musdah. "Muslim Family Law Reform in Indonesia: A Progressive Interpretation of The Qur’an." Al-Mawarid: Jurnal Hukum Islam (2015): 1-18. The term also implies that humans need to renounce claiming divine status for themselves by regarding themselves as better than others. Besides worshipping only one God, it also postulates that God must be considered as entirely unique and condemns anthropomorphization. Shirk further implies that God's attributes cannot be associated with any other entity or that any other entity can exist independent from God. At the same time, shirk contains additional assumptions not entailed by the concept of idolatry and does not require a physical object of worship.Sinai, N. (2018). Polytheism. In K. Fleet, G. Krämer, D. Matringe, J. Nawas and D. J. Stewart (eds.), Encyclopaedia of Islam Three Online. Brill. https://doi.org/10.1163/1573-3912_ei3_COM_46230

Forms of shirk Shirk is classified into two categories:Winter, Timothy, ed. The Cambridge companion to classical Islamic theology. Cambridge University Press, 2008. p. 233 Shirk al-akbar (; ): open and apparent Shirk al-asghar or al-shirk al-khafi (; ): concealed or hidden. It is when people perform the necessary rituals, not for God but for the sake of others, including social recognition. Hidden shirk might be unwitting, yet punishable, although to a lesser extent than greater forms of shirk.

Ash-Shirk al-Akbar Ash-Shirk al-Akbar (Arabic:الشرك الأكبر) is defined as the most major type of open association. It has been described in four forms:

Shirk-ad-Du'a Shirk-ad-Du'a (Arabic: شِرْكُ الدُّعَاءِ) is when on invokates, supplicates, or prays to anyone other and God alone. The Quran says in Al-Ankabut V. 65:

Shirk-al-Niyyah wal-Irada wal Qasd Shirk-al-Niyyah wal-Irada wal Qasd (Arabic: الشرك في النية والإرادة والقصد) is when one has the intention, purpose and determination to perform an act of worship or good deed for the sake of other deities than God.

Shirk-at-Ta'a Shirk-at-Ta'a (Arabic: شرك الطاعة) is when one obeys any other religious authority against the orders of God. Regarding this, the Quran says in At-Tawbah V. 31:

Shirk-al-Muhabbah Shirk-al-Muhabbah (Arabic: شرك المحبة) is when shows love to others which is due to God. This is seen in Al-Baqarah V. 165:

Shirk al-asghar Shirk al-asghar (Arabic: شرك الأصغر) may be committed by one who professes tawhid, but for the sake of others.

Mahmud ibn Lubayd reported:

Mahmud ibn Lubayd also said:

Umar ibn al-Khattab narrated that Muhammad said: "Whoever swears by other than Allah has committed an act of kufr or shirk." (graded hasan by Al-Tirmidhi and saheeh by Al-Hakim)

According to Ibn Mas'ud, one of Muhammad's companions said: "That I should swear by Allah upon a lie is more preferable to me than that I should swear by another upon the truth."Muhammad ibn Abd al-Wahhab, Kitab At-Tawheed, chapter 40

Sufism According to Sufi teachings, to avoid "hidden shirk" (), it is necessary to focus solely on God and give up one's own will.Sands, Kristin. Sufi commentaries on the Qur'an in classical Islam. routledge, 2006. p. 29

Some Sufi scholars even go so far as to describe a belief in free will as a form of shirk. According to such an uncompromising view, beliefs usually accommodated within monotheism, such as that in a personal devil (rather than the unregenerate self deficient in God) as the source of evil, or a belief in the concept of free will, are regarded as beliefs in creative powers other than (i.e., standing beside/external to) God, and are thus equated with shirk.Awn, Peter J. (1983). Satan's Tragedy and Redemption: Iblīs in Sufi Psychology. Leiden: Brill Publishers. p. 104.

Abdullah Ansari describes the highest stage of tawhid a human can possess, when the mind becomes fully immersed in the presence of God and understand how all things are put into their proper places.Abdullah, Wan Suhaimi Wan. "Herawi's Concept of Tawhid: An Observation Based on His Manazil Al-Sa'irin." Jurnal Usuluddin 12 (2000): 95-104.

In Sufism, every action done with an expectation of reward, either in this world or in the hereafter, is considered an act of shirk. Despite that this level of shirk does not entail disbelief, or require repeating the action to follow Islam's legal prescriptions, Sufis work on purification until their thoughts are not dominated by any desire except the pure love of God, which results in pure actions of worship.

Salafism and Wahhabism Muhammad ibn Abd al-Wahhab, founder of the Wahhabi movement, classified shirk into three main categories.Peskes, Esther and Ende, W., “Wahhābiyya”, in: Encyclopaedia of Islam, Second Edition, Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Consulted online on 25 February 2024 First published online: 2012 First print edition: , 1960-2007 However, ibn Taymiyya is considered to have been the spiritual founder of this distinction.

tawhid al-rububiyyah (Lordship): the verbal profession that God (Allah) is the sole creator and ruler over the world. tawhid al-Asma wa's-Sifat (names and attributes): accepting the attributes of God as written in the Quran without interpretation.