The concept of Tawhid

Tawhid is the religion's central and single most important concept upon which a Muslim's entire religious adherence rests. It unequivocally holds that God is indivisibly one (ahad) and single (wahid).[3][4]

Tawhid constitutes the foremost article of the Muslim profession of submission.[5] The first part of the Islamic declaration of faith (shahada) is the declaration of belief in the oneness of God.[3] To attribute divinity to anything or anyone else, is considered shirk, which is an unpardonable sin unless repented afterwards, according to the Qur'an.[6][7] Muslims believe that the entirety of the Islamic teaching rests on the principle of tawhid.[8]

From an Islamic standpoint, there is an uncompromising nondualism at the heart of the Islamic beliefs (aqida) that is seen as distinguishing Islam from other major religions.[9]

The Quran teaches the existence of a single and absolute truth that transcends the world, a unique, independent and indivisible being that is independent of all of creation.[10] God, according to Islam, is a universal God, rather than a local, tribal or parochial one and is an absolute that integrates all affirmative values.[6]

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 tawhid. Islamic scholars have different approaches toward understanding it. Islamic scholastic theology, jurisprudence, philosophy, Sufism, and even the Islamic understanding of natural sciences to some degree, all seek to explain at some level the principle of tawhid.[11]

The classical definition of tawhid was limited to declaring or preferring belief in one Allah and the unity of Allah.[12] Although the monotheistic definition has persisted into modern Arabic, it is now more generally used to connote "unification, union, combination, fusion; standardization, regularization; consolidation, amalgamation, merger".[13]

Chapter 112 of the Qur'an, titled al-Ikhlas, readsEtymology
The word 'tawhid' (توحيد), which means "He asserted, or declared, God to be one", is derived from the Arabic root 'wahhada' (واحدة), which means "to unite" or "to make one".[12][14] This term signifies the belief in absolute oneness and uniqueness of God.[15] This reflects the struggle of monotheism against polytheism.[16][17]

Name of God in Islam
Main article: Name of God in Islam
In order to explain the complexity of the unity of God and of the divine nature, the Qur'an uses 99 terms, which are referred to as "Excellent Names of God" (7:180). The divine names project divine attributes, which in turn project all the levels of the creation down to the physical plane.[18] Aside from the supreme name "Allah" and the neologism ar-Rahman (referring to the divine beneficence that creates and maintains the universe) and a few other specific names like Malik al-Muluk ("King of Kings") in an authentic narration of Muhammad, other names may be shared by both God and human beings. According to 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 a denial of the truth of God and thus is a major sin.[10]