Abstract
In Faith, Reason and the Existence of God, Denys Turner defends the possibility of proving God’s existence on Christian and philosophical grounds. He responds to Kantian objections by developing a theory of reason derived from Thomas Aquinas. Turner’s work shifts the debate about God’s existence to the problem of determining which concept of reason is correct. I argue that this problem is extremely difficult and perhaps insoluble, because it requires using reason to resolve a dispute about reason. Consequently, Turner’s claims cannot be accepted without reservation.