In reality, what they claim to know through reason consists only of mental universals, existing in the mind but having no reality in the external world. The abstract intelligibles they affirm—indeed, even the Necessary Existent they affirm, and other such things—amount to this.

This is how their fellow philosophers—the naturalists and the Dahriyya—gained the upper hand over them. The latter did not deny such objects of rational knowledge; rather, they denied their existence in the external world and claimed that whatever exists externally must be perceptible to the senses. Both groups rejected the Book and the tidings of the unseen with which Allah sent His messengers, except for those among them who were upright, monotheistic Sabians, believing in Allah and the Last Day and doing righteous deeds. These will enjoy happiness in the Hereafter, as the Most High says:

“Indeed, those who believe, the Jews, the Christians, and the Sabians—whoever believes in Allah and the Last Day and does righteous deeds—will have their reward with their Lord. No fear will there be concerning them, nor will they grieve.”

As for the polytheistic Sabians who worship celestial bodies and idols, and other polytheistic philosophers like them, they are disbelievers, like all other polytheists.

Greek philosophy—the philosophy of the Peripatetics—belongs for the most part to this kind of philosophy. The Greeks were polytheists who worshipped celestial bodies and idols. Their doctrines contain both truth and falsehood, as do the doctrines of the polytheists among the Arabs, Indians, and other groups. This is discussed at length elsewhere.