As the Exalted One says:

“Shall I inform you upon whom the devils descend? They descend upon every habitual liar, every sinner.”
(al-Shuʿarāʾ 221–222)

When a person is one of Allah’s righteous allies—God-fearing and obedient to Allah and His Messenger—the devils flee from him. His supporters are the hosts of Allah: the angels, the believing jinn, and others besides. At times the devils may even comply with a friend of Allah in certain matters that constitute obedience to Allah and His Messenger, doing so in reverence and deference to that servant rather than out of obedience to Allah and His Messenger. Such incidents occur frequently, yet no one other than Solomon—peace be upon him—was ever granted absolute dominion over jinn and devils. A full discussion of this lies elsewhere.

The point relevant here is that these philosophers often suppose that the intelligible notions conceived in the mind are actual, external realities. This assumption dominates much of their discourse, and whoever notices it will discern the source of their error in many of their conclusions. Admittedly, they possess intellect, reflection, and a measure of merit when compared with their own followers—but not when compared with the followers of the Messengers.

The sciences they truly mastered were medicine and mathematics. Consequently, they produced extensive and generally sound writings on natural philosophy, and likewise on mathematics—both in discrete quantity and in continuous quantity. Yet they are sharply divided in astronomy, concerning the movements and sizes of the heavenly bodies, and the same divergence appears in their other sciences; indeed, they are the most contentious of all sects.

Thus, when Abū ʿAbd Allāh al-Rāzī states, “The philosophers are in agreement,” he is referring only to what Ibn Sīnā recorded in his works and to the opinions of the Peripatetics, the followers of Aristotle. In reality, philosophers are of many different kinds, and Abū al-Ḥasan al-Ashʿarī has noted in his book