Ecclesiology is now taken for granted as an area of theological research. Before the modern age, however, the Church felt no need to define itself. What Father Tavard presents in this work is a systematic organization of the essential Christian beliefs about what the Church has been, is, and ought to be. It focuses on the awareness of 'being' Church that is inseparable from the profession of the Christian faith. Keeping the present historical moment in mind, Tavard investigates the dogmatic or doctrinal nature and structure of the Church in an ecumenical spirit.