There are a lot of misconceptions about both Ecumenism and the Catholic Church. Many people equate ecumenism with the World Council of Churches…an organization that has sunk into near oblivion and bankruptcy. In this equation ecumenism is a kind of ecclesiastical United Nations; a talking shop where church leaders meet to work together for peace and justice. The WCC is thought of as a global Christian confederation, and those who see the WCC as the voice of ecumenism usually hold that further formal unity is un-necessary. Instead the WCC simply has to do its work more effectively.
That the Catholic Church has never joined the WCC has been somewhat of a sore spot. At the same time, the Catholic Church has, over the last forty years, been the front runner in the search for church unity. Time and again, around the world and with every conceivable Christian group, the Catholic Church has reached out the loving hand of friendship.
For an understanding of the principles of Catholic ecumenism I encourage you to read the V2 decree on ecumenism: UNITATIS REDINTEGRATIO
At the heart of the document is the spirit of the Catholic Church’s attitude to ecumenism: it is open, humble and asking forgiveness. Here are a few quotes:
Even in the beginnings of this one and only Church of God there arose certain rifts, which the Apostle strongly condemned. But in subsequent centuries much more serious dissensions made their appearance and quite large communities came to be separated from full communion with the Catholic Church-for which, often enough, men of both sides were to blame. The children who are born into these Communities and who grow up believing in Christ cannot be accused of the sin involved in the separation, and the Catholic Church embraces upon them as brothers, with respect and affection.
it remains true that all who have been justified by faith in Baptism are members of Christ’s body, and have a right to be called Christian, and so are correctly accepted as brothers by the children of the Catholic Church.
Catholics must gladly acknowledge and esteem the truly Christian endowments from our common heritage which are to be found among our separated brethren. It is right and salutary to recognize the riches of Christ and virtuous works in the lives of others who are bearing witness to Christ, sometimes even to the shedding of their blood. For God is always wonderful in His works and worthy of all praise.
Nor should we forget that anything wrought by the grace of the Holy Spirit in the hearts of our separated brethren can be a help to our own edification. Whatever is truly Christian is never contrary to what genuinely belongs to the faith; indeed, it can always bring a deeper realization of the mystery of Christ and the Church.
There can be no ecumenism worthy of the name without a change of heart. For it is from renewal of the inner life of our minds, from self-denial and an unstinted love that desires of unity take their rise and develop in a mature way. We should therefore pray to the Holy Spirit for the grace to be genuinely self-denying, humble. gentle in the service of others, and to have an attitude of brotherly generosity towards them.
The words of St. John hold good about sins against unity: “If we say we have not sinned, we make him a liar, and his word is not in us”. So we humbly beg pardon of God and of our separated brethren, just as we forgive them that trespass against us.