The Brethren of Purity (Ikhwān al-Ṣafā’) were a tenth century CE Ismāʿīlī philosophical group that flourished in Basra, Iraq. Little is known about the actual group or its members, and their only remains are 52 epistles and two summaries. However, their works played an influential role in various intellectual trajectories throughout Islamic and Jewish philosophical history. I argue that the Brethren’s conception of God demonstrates how they combined Qur’ānic symbols with Ismāʿīlī Hermetic and NeoPythagorean ontology and Neoplatonic cosmology to chart a way by which human beings can bring themselves closer to God. In this paper, I show how God is addressed in the two Treatises and their summaries. Although the Treatises have been translated, a study of the influence of this Treatises and their summaries has yet to be undertaken. In the first treatise, entitled On “Arithmetic,” the Brethren address the role of God. They begin with an invocatory statement, “Know oh Brother, may God provide you and us with a spirit from Him.” This statement says two things which are important for cosmology. First, that despite the Neoplatonic emanationist model which they follow, they insist on God’s direct intervention in the lives of individuals. Second, the request for God to provide a spirit instead of His direct help is indicative of their Hermetic theurgical beliefs. In their 33rd Treatise, entitled On the Intellectual Principles According to the Views of Pythagoras, the Brethren of Purity begin by stating that God, “the Creator, Blessed and Exalted, is of perfect Existence, complete in excellences, fully knowing about beings before they are, and able to bring them into being whenever He wishes.” They then employ Qurʾānic verses to substantiate their claim. For example, they cite the 112th chapter of the Qurʾān stating that God is the “One, the Unique, the Eternally Sufficient unto Himself. He begets not; nor was He begotten. And none is like unto Him.” Using Pythagorean ontology and language, the Brethren of Purity argue that the One, Creator, Light, and Perfection are all found in God. They begin their Summary of the Treatises by citing the Qurʾān’s 87th chapter, confirming their belief that only through God’s guidance can human beings achieve spiritual success. The Brethren of Purity’s Treatises constantly emphasize God’s transcendence and immanence. They also emphasize God’ knowledge of all things, role in creating and destroying the world.