Noted for its impact by supporters and detractors alike, the Anscombe-Lewis debate was about the fundamental philosophical propositions that underpin Christianity; but more than that, it illustrates and defines a point where Lewis’s work changes, a shift in his theological method. From a philosophical perspective the debate centres on Lewis’s censure of Naturalism and Scientism. Anscombe’s criticism of Lewis’s key argument against Naturalism (the argument from reason) revealed a minefield in terms of causation and our use of language, however, Lewis’s response (the rewriting of Miracles, 2nd edition, 1960) illustrates his mature theological understanding of revelation and reason, and thereby foundationalism. Underpinning Lewis’s work is a symbiotic relationship between revelation and reason; Lewis did not see a dichotomy between the two: religion is rational, and reason is religious—importantly, reason precedes nature, it does not issue from nature. It is intended to demonstrate how Lewis’s championing of apologetics through the analogia entis (the analogy of being) in the 1930s and 1940s takes a more cautious, reflective and nuanced line in the 1950s; reason is complemented by wisdom though his use of the analogia fidei (the analogy of faith). Essentially this contradicts the critics who assert that, following the debate, Lewis abandoned rational apologetics for children’s stories. This shift in method is gradual, a development from the analogia entis to the analogia fidei, not necessarily triggered by the debate alone (perhaps accelerated), but a fuller development and use of a method already present. Reason and imagination now reveal of God’s purposes and truth through word pictures and narrative—faith leads to understanding (fides quaerens intellectum), faith is the ground from which reason can work. This relates closely to a concern for Christlikeness (which is consistently evidenced in his mature work): can analogical narrative tell us more of the truth of revelation than philosophical discourse?