Abstract
We gain insight into how Christianity has changed by seeing it divided into three great periods: (1) the Platonic Christianity of the church fathers, (2) the Aristotelian Christianity of the Middle Ages, and (3) the Kantian Christianity of the modern era. This division does not mean that Platonic and Aristotelian Christianity (Augustinianism and Thomism) do not persist into the twenty-first century. It does mean that they have been modified by incorporating new elements, mainly, I claim, from Kantian philosophy. Whether or not this claim is sound is the point that Professor Jeffreys and I are debating in order to shed light on the current state of Christian theology and its implications for politics and ethics.