The doctrine about God in the Qur'an is rigorously monotheistic: God is one and unique; he has no partner and no equal. Trinitarianism, the Christian belief that God is three persons in one substance, is vigorously repudiated. Muslims believe that there are no intermediaries between God and the creation that he brought into being by his sheer command: "Be." Although his presence is believed to be everywhere, he does not inhere in anything. He is the sole Creator and sustainer of the universe, wherein every creature bears witness to his unity and lordship. But he is also just and merciful: his justice ensures order in his creation, in which nothing is believed to be out of place, and his mercy is unbounded and encompasses everything. His creating and ordering the universe is viewed as the act of prime mercy for which all things sing his glories. The God of the Qur'an, described as majestic and sovereign, is also a personal God; he is viewed as being nearer to man than man's jugular vein, and, whenever a person in need or distress calls him, he responds. Above all, he is the God of guidance and shows everything, particularly man, the right way, "the straight path."
This picture of God--wherein the attributes of power, justice, and mercy interpenetrate--is related to the Judeo-Christian tradition, whence it is derived with certain modifications, and also to the concepts of pagan Arabia, to which it provided an effective answer. The pagan Arabs believed in a blind and inexorable fate over which man had no control. For this powerful but insensible fate the Qur'an substituted a powerful but provident and merciful God. The Qur'an carried through its uncompromising monotheism by rejecting all forms of idolatry and eliminating all gods and divinities that the Arabs worshipped in their sanctuaries (harams), the most prominent of which was Ka'bah sanctuary in Mecca itself.