Muslim-Christian Theological Controversies about the Trinity during the First Centuries of the Hegira

The doctrine of the Trinity has long been a source of controversy within the Christian world. Over time, this belief also became one of the central topics in theological debates between Christians and Muslims. During the first five centuries of the Islamic era, Christian theologians living in the Muslim world, such as the Melkite Theodore Abū Qūrrāh (d. ca. 829), the Nestorian ʿAmmār al-Baṣrī (d. ca. 850), and the Jacobite Abū Raʾīṭah al-Takrītī (755–835), wrote numerous works in defense of the Trinity. Through various methods and arguments, they sought to present themselves as monotheists. To this end, they attempted to explain the Trinity using Islamic theological methods and concepts. In response, Muslim Muʿtazilite theologians such as Abū ʿĪsā al-Warrāq (d. 247/861) and ʿAbd al-Jabbār (d. 415/1024), along with many other heresiographers and apologists, composed treatises refuting the doctrine of the Trinity. They rejected and refuted all the arguments advanced by Christian writers in its defense, striving to demonstrate that Christians were, in fact, tritheists. This thesis first explains the evolution of the concept of the Trinity within mainstream Christianity up to the Council of Chalcedon. It then turns to the idea of the Trinity among the so-called heretical Christian sects and apocryphal gospels. The study also examines how the Qur’an, Muslim exegetes, historians, and heresiographers viewed the Trinity and related concepts. Throughout this work, we have sought to analyze Muslim understandings of the Trinity and other Christian doctrines as objectively as possible, employing a phenomenological approach combined with critical analysis.