Fundamental theological issues arise in the field of tension that lies between creation and fulfillment. How to be Christians amidst the world's great religions? How to profess the Creed here and now, yet keep the desire for God alive? How to believe without being torn apart by too nervous a desire for certainty and too rarified a sense of the world to come? Most of all: just what is Christianity? This book answers: the portrayal of the living God by a community forever in transition between creation and full pasticipation in the life of God. Transition also defines what theology itself must be: reasoned without giving in to rationalism and open to God's self-revelation without yielding to supernaturalism. This book, while conceived as part of a whole system of Catholic theology, offers a coherent fundamental theology in and of itself.