More than six centuries separate the death of Saint Augustine (354-430) and thebirth of Abu Hamid Al-Ghazali (1058-1111). Each of these two 'giants of the spirit' professeda different faith, and struggled with different social and political life. Augustine lived in thefourth and fifth-century Carthage, Rome, Milan and Hippo; Al-Ghazali in the eleventh andtwelfth-century Baghdad, Damascus, Mecca and Tus. But the readers of the spiritual autobiographiesleft behind by Augustine and Al-Ghazali will certainly be amazed to find strikingsimilarities that refl ect a common struggle with the same existential questions about theparadoxes of the human condition and the perpetual search and longing for God. A solidscholarship, a great curiosity and a genuine thirst for certainty were characteristic of bothAugustine and Al-Ghazali. Each of these two seekers of God immersed himself bravely inunfamiliar cultures, bridged different worlds, and subdued whatever he studied to his faith.The process of this cultural digestion did not pass without painful impact on these giantminds, not the least of it is the spiritual restlessness that Augustine and Al-Ghazali hadto struggle with, and to make their way through, with a great difficulty and agony. Thisarticle emphasizes the quest for spiritual certainty in the autobiographies of Augustine andAl-Ghazali, as opposed to the quest for intellectual certainty, commonly associated withthese two seekers of God.