In an effort to resolve the systematic ambiguities in today's use of the term "theology of religions," Heung-Gyu Kim has written Prolegomena to a Christian Theology of Religions. Kim critically analyzes the core issues in Christianity's approach to religious plurality: defining "religion" and "religious" in terms of the common essence and manifestation model, the challenges of religious plurality to Christian faith, and the relationship of a theology of religions to systematic theology. He also explores various models of this theology, as represented by Karl Barth, Karl Rahner, John Hick and Schubert Ogden.