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and the Naturalists, and exposed their defects so effectively that others
were relieved of the task. “And Allah relieved the believers of fighting”
(Koran 33, 25) through their mutual combat. Aristotle even attacked
predecessor Theistic philosophers, especially Plato and Socrates, and went
so far in his criticisms that he separated himself from them all. Yet he too
retained a residue of their unbelief and heresy from which he did not
manage to free himself. We must therefore call them unbelievers, both
these philosophers and their followers among the Islamic philosophers,
such as Ibn Sina, Al-Farabi, and others; in transmitting the philosophy of
Aristotle, however none of the Islamic philosophers has accomplished
anything comparable to the achievements of the two men named. The
translations of others are marked by disorder and confusion, which confuse
the student so much that he fails to comprehend; and if a thing is not
comprehended how can it be either refuted or accepted?

All that is part of the philosophy of Aristotle and falls under three heads:

(1) what must be counted as unbelief; (2) what must be counted as heresy;