Tawhid is the concept of monotheism in Islam. It is the religion’s most fundamental concept and holds God(Arabic: Allah) is one (wāḥid) and unique (ahad).

The Qu’ran asserts the existence of a single and absolute truth that transcends the world; a unique, independent and indivisible being, who is independent of the entire creation. The indivisibility of God implies the indivisibility of God’s sovereignty which, in turn, leads to the concept of a just, moral and coherent universe, as opposed to an existential and moral chaos^{[citation needed]}. Similarly, the Qur’an rejects the concept of duality of God arguing that good generate from God’s creative act and evil from free will of creation, asserting that the evil forces have no power to create anything. God according to Islam is a universal God, rather than a local, tribal or parochial one—is an absolute, who integrates all affirmative values and brooks no evil.

Tawhid constitutes the foremost article of the Muslim profession. The first part of the Shahada is the declaration of belief in the oneness of God. To attribute divinity to a created entity is the only unpardonable sin mentioned in the Qur’an. Muslims believe that the entirety of the Islamic teaching rests on the principle of Tawhid. There is an uncompromising monotheism at the heart of the Islamic beliefs which distinguishes Islam from some other major religions.

Islamic intellectual history can be understood as a gradual unfolding of the manner in which successive generations of believers have understood the meaning and implications of professing God’s Unity. Islamic scholars have different approaches toward understanding it. Islamic theology, jurisprudence, philosophy,Sufism, even to some degree the Islamic understanding of natural sciences, all seek to explain at some level the principle of tawhid.

Tawhid in the Qur’an

The Qur’an is the main information source for understanding the oneness of God in Islam. All Muslim authorities maintain that a true understanding of God is impossible unless He introduces Himself due to the fact that God is beyond the range of human vision and senses^{[citation needed]}. Therefore God tells people who He is by speaking through the prophet. According to this view the fundamental message of all of the prophets is “There is no God worthy of worship but God.”

The Qur’an asserts the existence of a single, absolute truth that transcends the world; a unique being who is independent of the creation; a real being indivisible into hypostatic entities or incarnated manifestation. According to the Qur’an:

“Say (O Muhammad(saas)): “He is God, (the) One, The Self-Sufficient Master, He begets not, nor was He begotten; And there is none co-equal or comparable unto Him.” (Sura 112:1-4)
“Thy Lord is self-sufficient, full of Mercy: if it were His will, He could destroy you, and in your place appoint whom He will as your successors, even as He raised you up from the posterity of other people.”(Sura 6:133)

According to Vincent J. Cornall, the Qur’an also provides a monist image of God by describing the reality as a unified whole, with God being a single concept that would describe or ascribe all existing things:”He is the First and the Last, the Evident and the Immanent: and He has full knowledge of all things.”(Sura 57:3)” Some Muslims have however vigorously criticized interpretations that would lead to a monist view of God for what they see as blurring the distinction between the creator and the creature, and its incompatibility with the genuine and absolute monotheism of Islam.

The Qur’anic passages Sura 34:20-24, Sura 35:40 and Sura 46:4 provide a basic understanding of the serious nature and consequences of assigning partners or equals to God, a sin known in Islam as Shirk. God will forgive any sin except a person who dies while committing Shirk. The verse 34:20-24 rejects the idea of duality of God by arguing that both good and evil generate from God’s creative act and that the evil forces have no creative power.

The Qur’an relates the story of Abraham in order to provide an example of an intellectual quest for understanding God as the Cause of Causes: Related in verses 6:75-79, Abraham moves progressively from worshipping the stars, the moon, and the sun to acknowledging God as the sole cause of the heavenly phenomena.

In order to explain the complexity of unity of God and of the divine nature, the Qur’an uses 99 terms referred to as “Excellent Names of God” (Sura 7:180). Aside from the supreme name “Allah” and the neologism al-Rahman (referring to the divine beneficence that creates and maintains the universe), other names may be shared by both God and human beings. According to the Islamic teachings, the latter is meant to serve as a reminder of God’s immanence rather than being a sign of one’s divinity or alternatively imposing a limitation on God’s transcendent nature. Attribution of divinity to a created entity, shirk, is considered as a denial of the truth of God and thus a major sin.