Despite his declared reluctance to enter into theological discussions, al-Ghazâlî addresses in his Revival important philosophical problems related to human actions. In the 35th book on “Belief in Divine Unity and Trust in God” (Kitâb al-Tawhîd wa-l-tawakkul) he discusses the relationship between human actions and God's omnipotence as creator of the world. In this and other books of the Revival al-Ghazâlî teaches a strictly determinist position with regard to events in the universe. God creates and determines everything, including the actions of humans. God is the only “agent” or the only “efficient cause” (fâ’il, the Arabic term means both) in the world. Every event in creation follows a pre-determined plan that is eternally present in God's knowledge. God's knowledge exists in a timeless realm and does not contain individual “cognitions” (‘ulûm) like human knowledge does. God's knowledge does not change, for instance, when its object, the world, changes. While the events that are contained in God's knowledge are ordered in “before” and “after”, there is no past, present, and future. God's knowledge contains the first moment of creation just as the last, and He knows “in His eternity,” for instance, whether a certain individual will end up in paradise or hell (Griffel 2009, 175–213).

For all practical purposes it befits humans to assume that God controls everything through chains of causes (Marmura 1965, 193–96). We witness in nature causal processes that add up to longer causal chains. Would we be able to follow a causal chain like an “inquiring wayfarer” (sâlik sâ’il), who follows a chain of events to its origin, we would be led through causal processes in the sub-lunar sphere, the “world of dominion” (‘âlam al-mulk), further to causes that exist in the celestial spheres, the “world of sovereignty” (‘âlam al-malakût), until we would finally reach the highest celestial intellect, which is caused by the being beyond it, God (al-Ghazâlî 1937–38, 13:2497–509 = 2001, 15–33; see also idem 1964a, 220–21). God is the starting point of all causal chains and He creates and controls all elements therein. God is “the one who makes the causes function as causes” (musabbib al-asbâb) (Frank 1992, 18).

God's “causal” determination of all events also extends to human actions. Every human action is caused by the person's volition, which is caused by a certain motive (dâ’iya). The person's volition and motive are, in turn, caused by the person's convictions and his or her knowledge (‘ilm). Human knowledge is caused by various factors, like one's experience of the world, one's knowledge of revelation, or the books one has read (al-Ghazâlî 1937–38, 13:2509–11 = 2001, 34–37). There is no single event in this world that is not determined by God's will. While humans are under the impression that they have a free will, their actions are in reality compelled by causes that exist within them as well as outside (Griffel 2009, 213–34).

Al-Ghazâlî viewed the world as a conglomerate of connections that are all pre-determined and meticulously planned in God's timeless knowledge. God creates the universe as a huge apparatus and employs it in order to pursue a certain goal (qasd). In two of his later works al-Ghazâlî compares the universe with a water-clock. Here he describes three stages of its creation. The builder of the water-clock first has to make a plan of it, secondly execute this plan and build the clock, and thirdly he has to make the clock going by supplying it with a constant source of energy, namely the flow of water. That energy needs to be carefully measured, because only the right amount of energy will produce the desired result. In God's creation of the universe these three stages are called judgment (hukm), decree (qadâ’), and pre-destination (qadar) (al-Ghazâlî 1971, 98–102; 1964a, 12–14). God designs the universe in His timeless knowledge, puts it into being at one point in time, and provides it with a constant and well-measured supply of “being” (wujûd). According to Avicenna's explanation of creation—which al-Ghazâlî was not opposed to—“being” is passed down from God to the first and ontologically highest creation and from there in a chain of secondary efficient causes to all other existents. It is important to acknowledge, however, that God is the only true efficient cause (fâ’il) in this chain. He is the only “agent,” all other beings are merely employed in His service (Griffel 2009, 236–53).

Nature is a process in which all elements harmoniously dovetail with one another. Celestial movements, natural processes, human actions, even redemption in the afterlife are all “causally” determined. Whether we will be rewarded or punished in the afterlife can be understood, according to al-Ghazâlî, as the mere causal effect of our actions in this world. In the 32nd book of his Revival al-Ghazâlî explains how knowing the Qur’an causes the conviction (i’tiqâd) that one is punished for bad deeds, and how that conviction may cause salvation in the afterlife:

…and the conviction [that some humans will be punished] is a cause (sabab) for the setting in of fear, and the setting in of fear is a cause for abandoning the passions and retreating from the abode of delusions. This is a cause for arriving at the vicinity of God, and God is the one who makes the causes function as causes (musabbib al-asbâb) and who arranges them (murattibuhâ). These causes have been made easy for him, who has been predestined in eternity to earn redemption, so that through their chaining-together the causes will lead him to paradise. (al-Ghazâlî 1937–38, 11:2225.)
All these are teachings that are very close to those of Avicenna (Frank 1992, 24–25). Al-Ghazâlî also followed Avicenna in his conviction that this universe is the best of all possible worlds and that “there is in possibility nothing more wondrous than what is” (laysa fî-l-imkân abda’ mimmâ kân) (al-Ghazâlî 1937–38, 13:2515–18 = 2001, 47–50). This led to a long-lasting debate among later Muslim theologians about what is meant by this sentence and whether al-Ghazâlî is, in fact, right (Ormsby 1984). It must be stressed, however, that contrary to Avicenna—and contrary to Frank's (1992, 55–63) understanding of him—al-Ghazâlî firmly held that God exercises a genuine free will and that when He creates, He chooses between alternatives. God's will is not in any way determined by God's nature or essence. God's will is the undetermined determinator of everything in this world.