During these last decades the problem of Christian disunity has imposed itself on the conscience of Christians as an immediate challenge and there have been many attempts to find a solution. All Christians, whatever their ecclesiastical allegiance, affirm belief in ‘one, holy, cathohc and apostolic Church', and although no mark of the Church could exist independently of the others, it is natural to seek the answer to the problem raised by Christian disunity first in terms of the note of uniqueness.

We could divide Christians into two groups: those who believe that the note of one-ness is already fully exemplified in their own Church, as is the case with Catholics and with Orthodox Christians; and those who represent various Protestafant traditions and who, while affirming belief in ‘one Church', also believe that the unity of the Church has to be re-asserted and made manifest because the visible unity has been destroyed by divisions among Christians which have come about since the first centuries A.D.