Al-Ghazali surveys four groups who claimed access to religious truth: the theologians (mutakallimun), the philosophers (falasifa), the Ismaili Shi'a who appealed to infallible imams, and the Sufis who claimed mystical experience. He finds each of the first three inadequate in different ways: the theologians presuppose what they should prove, the philosophers contradict revelation, and the Ismailis offer blind deference rather than genuine knowledge.
The Sufis alone, Al-Ghazali concludes, have genuine access to religious truth — not because they offer better arguments but because their method is experiential rather than theoretical. Like the difference between knowing that honey is sweet from a description and knowing it from tasting, Sufi knowledge of the divine is direct, immediate, and self-authenticating. It cannot be transmitted in propositions but only in the transformative practice of the spiritual path.
Dhawq is inseparable from moral transformation: mystical experience is available only to those who have disciplined their souls, controlled their passions, and cultivated the inward virtues. This means that genuine religious knowledge requires ethical preparation — the philosopher who seeks truth without first purifying the soul is like a blind man seeking to see by polishing a mirror he cannot look into.
Al-Ghazali's account of Sufi knowledge occupies the final section of Deliverance from Error, and was developed at length in his magnum opus, The Revival of the Religious Sciences.