The late Indian theologian-evangelist, D.T. Niles, relates the story of sitting in the 1954 Assembly of the World Council of Churches and listening to a great sermon by Archbishop Michael of the Orthodox Church. He said that for half an hour he listened to the bishop speak of the church as it is spoken of so wonderfully in the Bible. Then, without warning, the audience discovered that the bishop was talking about the Orthodox Church. The Episcopal Bishop of Washington leaned over to Niles and said, "D.T., she'll be coming 'round the mountain when she comes."
Niles goes on to say that this happens whenever one group of Christians, or another, begins to talk about the church. We think, in our own minds, that they are talking about the whole Christian church when in fact they are talking about our own church; e.g., Methodist, Presbyterian, Baptist, Anglican, Catholic, Orthodox, etc. Niles says it is true for all of us: "She'll be coming 'round the mountain when she comes!" There is a wide gulf between the church we confess when we say we believe in "one holy catholic church" and our own church or particular expression of the church.
I have found this to be the biggest barrier of all to serious ecumenism. My Catholic and Orthodox friends, whom I love and regard with deep esteem, still insist (over against each other as well as all Protestants) that one of them is "The Church." One has to be wrong and both know this much. Pope John Paul II desired the unity of the two ancient churches and saw little come of his efforts. Protestants have generally proven to be far more willing dialogue partners with Catholics than the Orthodox. In some ways this is an odd thing since the Eastern and Western churches were united for ten centuries and share a strong common bond in the way they read the early church fathers. This may say more about the power of culture to divide us than it does about theology, which makes it even more tragic to my mind.
If one studies this long enough they soon see that there were moments in church history when it could have been a very different story but those moments are now past. This has led many to conclude that no serious effort for unity should be undertaken now since there is no chance at all that we will ever solve the differences between us.
D.T. Niles expressed my view plainly when he wrote: "Our primary task is to ask God to tell us how we, in our day and generation, and in the places where God has put us, can so enter into the reality of the Church that those who see us can see in us and through us and by us the Church made visible—visible in beauty, visible in its freshness, visible as the bride and body of Christ. We do not change the Church. It is the Bride of Christ, the Body of Christ. All we can do and must do is to make that Church visible, a little more visible, that men may see it in its beauty and its power" (The Message and Its Messengers: Missions Today and Tomorrow, D. T. Niles, Abingdon Press, Nashville