Thauheed (Arabic: توحيد tawḥīd; English:doctrine of Oneness [of God]; also transliterated Tawheed, and Tauheed.) is theconcept of monotheism in Islam. It is the religion's most fundamental conceptand holds God (Arabic: Allah) is one (wāḥid) and unique (ahad).

The Qu'ran asserts theexistence of a single and absolute truth that transcends the world; a unique,independent and indivisible being.God according to Islam is a universal God,rather than a local, tribal or parochial one—is an absolute, who integrates allaffirmative values and brooks no evil.

Tawhid constitutes theforemost article of the Muslim profession. The first part of the Shahada is thedeclaration of belief in the oneness of God. To attribute divinity to a createdentity is the only unpardonable sin mentioned in the Qur'an. Muslims believethat the entirety of the Islamic teaching rests on the principle of Tawhid.There is an uncompromising monotheism at the heart of the Islamic beliefs whichdistinguishes Islam from some other major religions.

Islamic intellectualhistory can be understood as a gradual unfolding of the manner in whichsuccessive generations of believers have understood the meaning andimplications of professing God's Unity. Islamic scholars have differentapproaches toward understanding it. Islamic theology, jurisprudence,philosophy, Sufism, even to some degree the Islamic understanding of naturalsciences, all seek to explain at some level the principle of tawhid.