*Al-Arba'in fi Usul al-Din* (The Forty Principles of Theology) stands as one of the finest works authored by Imam Fakhr al-Din al-Razi concerning rational inquiries and the methods by which theological truths are established. Indeed, it represents one of the most effective approaches for engaging with non-Muslims—particularly in contexts where it is not possible to persuade them of theological matters through the use of scriptural evidence.