Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
We have been discussing a biased definition of unity as "uniting the Church", which obviously both Protestants and Orthodox/Catholic disagree, otherwise there wouldn't be division in the first place! Protestants have their own criticisms of the Church, and the Church has obvious criticisms about Protestantism, and so to be "united" with these is obviously stretch. Much like the Arabs and the Israelis, we may not be able to settle our existential differences, but surely we'll have to learn to get along one way or the other. I don't think that the unity of Christians which HIM was speaking of in 1971 was some kind of crypto-reunion, because such is realistically an impossibility. Simply put, if Protestants want to unite, all they have to do is be baptized and convert or return from their straying and be Chrismated back into their rightful fold. This is the only "unity" which could be acceptable to the Orthodox perspective, let alone the complications in reunion between Latins, Orthodox, and Orientals. However, I think the unity which HIM was implying is a function of acting in unison in social and political causes. We share inherent Christian values and political ideologies as well as cultural and psychological principles, we should be building on this. If we can't unite as One Church, the least we can do is begin to act more in unison as a society of Christians. It is the same as the expectations which HIM had for the plurality of the Ethiopian population, and which the American ideals aspire towards, that a pluralistic society can at least learn to get alone more or less. While the be united is surely an impossibility, to learn to cooperate and act in unison is surely a pragmatic goal. We all work with, attend school with, and are neighbors of many different kinds of people, and we seem to find a way to work out our differences and act in unison to get our jobs done, to succeed in our educations, and to live side by side as neighbors, shouldn't Christians, albeit theologically divergent, to at least settle for a neighborly cooperation? What is the mechanism of this acting towards unison, mutual dialogue. What do we need for dialogue, a mutual forum for discussion. This is precisely why HIM was a founding father of both the League of Nations, the United Nations, the Organization of African Unity, the Conference of Oriental Churches, and yes, even the World Council of Churches.
Unity is strength.