The Oneness of God in Islamic Theology: Qur’anic Foundations and Classical Rational Arguments

Abstract

This paper examines the concept of tawhid (Divine Oneness) in Islamic literature, exploring its foundation in the Qur’an and the rational arguments developed by classical Muslim philosophers and theologians. It begins with the Qur’anic foundation for monotheism, highlighting how the Qur’an itself provides an epistemic basis for recognizing one necessary cause behind all existence. Several major philosophical proofs for God’s unity are then analyzed, including Ibn Sina’s argument from contingency to a Necessary Existent, classical kalam arguments against the possibility of multiple gods (as articulated by Imam al-Haramayn al-Juwayni, al-Ghazali, and others), the argument from omnipotence, which shows that two omnipotent wills would conflict, and the argument from the unified order in the cosmos. The paper also examines the concept of Divine simplicity (non-composition) as argued in the Maturidi-Ashʿari tradition, the problem of joint causation and redundancy if multiple creators are posited, and finally the metaphysical perspective of Mulla Sadra, who frames Divine unity in terms of the unity of wujud (existence) itself. A synthetic discussion shows the convergence of revelation and reason: the Qur’anic worldview and classical logical arguments reinforce each other in affirming that God must be one. These approaches are also compared with perspectives in modern analytic philosophy of religion, illustrating the continued logical relevance of the classical proofs.

Keywords: Tawhid; Islamic Theology; Monotheism; Ibn Sina; Kalam; Contingency Argument; Omnipotence; Divine Simplicity; Mulla Sadra; Philosophy of Religion