This contribution discusses Leibniz’s conception of faith and its relation to reason. It shows that, for Leibniz, faith embraces both cognitive and non-cognitive dimensions: although it must be grounded in reason, it is not merely reasonable belief. Moreover, for Leibniz, a truth of faith (like any truth) can never be contrary to reason but can be above the limits of comprehension of human reason. The latter is the epistemic status of the Christian mysteries. This view raises the problem of how it can be determined whether a doctrine above the full grasp of human reason does or does not imply contradiction. The notion of ‘presumption’ and the ‘strategy of defence’ are presented and discussed as Leibniz’s way to tackle this issue. Finally, t...