The concept of tawḥīd (unity of God) is a central issue in Kalām theological treatises. The discussion devoted to this concept follows a typical structure, a fact that has been recognized by scholars in the past. Shlomo Pines points to the similarity between the Kalām model of discussion and the structure of John Damascene's (d. 750) De Fide Orthodoxa. Pines suggested that it may indicate the profound impact of Christian theology on Muʿtazilite Kalām. Ulrich Rudolph adds two important pieces of evidence to the discussion: He analyzes Abū Manṣūr al-Māturīdī al-Samarqandī's (d. 944) Kitāb al-Tawḥīd and the Jacobite Moses bar-Kepha's (d. 903) introduction to his Hexaemeron, and argues that the structural and conceptual affinity between them actually indicates an opposite direction of influence than the one suggested by Pines. According to Rudolph, the similarity of the two treatises shows they were written as an imitation of an older Muʿtazilite book, which constituted a prototype for the discussion on the concept of tawḥīd. This paper will challenge Rudolph's thesis in two ways, first by questioning his arguments concerning the sources of the Kitāb al-Tawḥīd, and second by suggesting an alternative assumption, which will strengthen Pines's theory regarding the development of the Kalām model of discussion. Through a comparative structural analysis of the works of Māturīdī and bar-Kepha, together with some fragments of earlier Jewish and Christian commentaries on Genesis, will rise the possibility that this model of discussion existed first in the Christian exegetical treatises assigned to Genesis and had already developed before it appeared in the Kalām works.