Fr Meyendorff affirms that one cannot "claim to be a Christian except through concrete membership in the catholic Church and through a continuous effort at manifesting the catholicity of the Church."

Avery Dulles, well-known for several previous works in ecclesiology, including Models of the Church, here surveys a theme that demands new treatment in the present global and ecumenical context. He deals with questions that are vital for the identity of churches that designate themselves Catholic, and for the relationship between these churches and Protestant forms of Christianity. The prospects of Catholicism are realistically appraised. The Catholicity of the Church reproduces, in slightly revised form, the Martin D'Arcy Lectures delivered by Fr Dulles at Campion Hall, University of Oxford. 'In theology such as this the seeds of real unity between divided Christendom are being sown.' B.L. Horne, 'This is a fine book, providing a framework for fruitful dialogues among Christians of all traditions.' Journal of Theological Studies Expository Times 'This is a refreshing and challenging book, and is of considerable ecumenical importance.' Oliver Rafferty, The Month 'At the heart of ecclesiology is the concept of catholicity, and in tackling the nature of the Church's catholicity Fr Dulles has courageously addressed himself to the crucial ecumenical question.' Roger Greenacre, Theology 'doing honour to the memory of Martin D'Arcy both for its realism and for its renewal of our sense of Catholicism.' Fergus Kerr, The Tablet