Tawhid (Arabic: توحيد tawḥīd; English: doctrine of Oneness [of God]; also transliterated Tawheed, and Tauheed.) 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. 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.