Aim of this article is to determine to what extent philosophy and ‘revealed message’ can be viewed separately in Leibniz’s Theodicy, in order to demonstrate that Leibniz’s texts seem to try to reconcile ‘reason’ and ‘revelation’, a complementarity justified by what can be called the ‘sanctity’ of reason. Leibniz’s reference to the ‘image of Divinity’ reveals that he refers to both ‘reason’ and ‘intelligence’, thus confirming his position in a well-rooted exegetical tradition that goes directly to the Late Classical concept of synderesis (συντήρησις). Although Leibniz does not explicitly use the term synderesis, he still refers to ‘pure reason’, a reason instilled in man by God and free of corruption. The conclusion in the last section examines some interesting passages in the Theodicy, § 91 and § 397, in which Leibniz deals with reason and original sin, and seems to hold that reason has somehow eluded the corrupting nature of original sin.