 Aquinas’s model of faith thus shares with the Reformed epistemologist model the problem that it leaves unanswered the reflective believer’s concern about entitlement. Attempting to settle that concern by meeting the evidential requirement leads to circularity: theological truths are to be accepted on divine authority, yet the truth that there is such an authority (historically mediated as the relevant tradition maintains) is amongst those very truths that are to be accepted on divine authority—indeed, it is the crucial one. As Descartes puts it in the Dedication to his Meditations, ‘It is of course quite true that we must believe in the existence of God because it is a doctrine of Holy Scripture, and conversely, that we must believe Holy Scripture because it comes from God. … But this argument cannot be put to unbelievers because they would judge it to be circular’ (Descartes 1641 [Cottingham et al. 1984, 3]). Thus, although they differ on the question whether the firm beliefs of faith count as knowledge, both Aquinas and Calvin understand faith as essentially involving accepting the truth of propositions as revealed through willingly receiving God’s gracious gift of that very revelation. The question remains how accepting this gift could be epistemically rational. The externalist account of how Christian beliefs may have epistemic worth proposed in Plantinga’s model of faith (named ‘the A/C’ model because its sources are supposedly found in Aquinas as well as Calvin) offers some help with the required explanation, but (as noted in the final paragraph of Section 4 above) may arguably not by itself be sufficient.