The theology and practice of the Eucharist is undoubtedly at the heart of the ecumenical task. The discussions on intercommunion and eucharistic hospitality have become the focus of nearly every ecumenical dialogue and of many ecumenical gatherings. Nevertheless I do not want to discuss this issue again here. For I am convinced that there will be no serious answer to the problem as long as we do not agree on some basic ecclesiological principles.
I want to deal with one of these basic principles. It is very strange indeed that so few theologians or churchmen have written on the link between Eucharist, Baptism and Church taken all together. Usually one studies the relation of Baptism with Church, of Eucharist with Church, of Baptism with Eucharist, but without putting together the result of these three analyses. I shall try to do it here. It will lead us to the very basic question of the distinction between the oneness (unicitas) and the Unity (Unitas) of the visible Church.