It is widely recognized nowadays that a moderate sceptical outlook can promote an attitude of tolerance towards views contrary to one’s own. By scepticism, we refer here not to doubt directed at one or more particular views, but to a general position of doubt towards the possibility of knowledge. This link between doubt and tolerance is a familiar feature of Islamic jurisprudence, but is hard to come by among theologians given their insistence that theological doctrines must be affirmed with unshakable certainty. This paper will examine an interesting case in which moderate doubt in a theological-cum-philosophical context engenders a surprising attitude of tolerance towards views that were normally condemned as tantamount to unbelief. The case in question occurs in a mature work of the 12th-century Fakhr al-Din Razi, one the most eminent and influential figures in pre-modern Arabic-Islamic thought.