Ecumenical means “universal.” Holy Mother Church uses “ecumenism” to describe the striving for reunification that she hopes will one day fulfill Rabbi Yeshua’s prayer.
Rabbi Yeshua’s Call
“Holy Father, keep them in thy name, which thou hast given me, that they may be one, even as we are one” Jn 17:11, cf. 22.
But He knew that we were not yet one. “And I have other sheep, that are not of this fold; I must bring them also, and they will heed my voice. So there shall be one flock, one shepherd” Jn 10:16.
Rabbi Paul added, “The bread which we break, is it not a participation in the body of Christ? Because there is one bread, we who are many are one body, for we all partake of the one bread” 1 Cor 10:16. In God’s wise providence every part of the body is needed. “The eye cannot say to the hand, “I have no need of you,” nor again the head to the feet, “I have no need of you” 1 Cor 12:21.
John Paul II’s Call
St. John Paul II, in Ut Unum Sint § 1, wrote:
Christ calls all his disciples to unity. My earnest desire is to renew this call today, to propose it once more with determination, repeating what I said at the Roman Colosseum on Good Friday 1994, at the end of the meditation on the Via Crucis prepared by my Venerable Brother Bartholomew, the Ecumenical Patriarch of Constantinople. There I stated that believers in Christ, united in following in the footsteps of the martyrs, cannot remain divided. If they wish truly and effectively to oppose the world’s tendency to reduce to powerlessness the Mystery of Redemption, they must profess together the same truth about the Cross. The Cross! An anti-Christian outlook seeks to minimize the Cross, to empty it of its meaning, and to deny that in it man has the source of his new life. It claims that the Cross is unable to provide either vision or hope. Man, it says, is nothing but an earthly being, who must live as if God did not exist.
St. John Paul II continued, § 3:
At the Second Vatican Council, the Catholic Church committed herself irrevocably to following the path of the ecumenical venture, thus heeding the Spirit of the Lord, who teaches people to interpret carefully the ‘signs of the times’. The experiences of these years have made the Church even more profoundly aware of her identity and her mission in history. The Catholic Church acknowledges and confesses the weaknesses of her members, conscious that their sins are so many betrayals of and obstacles to the accomplishment of the Savior’s plan. Because she feels herself constantly called to be renewed in the spirit of the Gospel, she does not cease to do penance. At the same time, she acknowledges and exalts still more the power of the Lord, who fills her with the gift of holiness, leads her forward, and conforms her to his Passion and Resurrection.
Vatican II’s Call
Vatican II’s Unitatis Redintegratio § 1 explained: “Christ the Lord founded one Church and one Church only. However, many Christian communions present themselves to men as the true inheritors of Jesus Christ; all indeed profess to be followers of the Lord but differ in mind and go their different ways, as if Christ Himself were divided. Such division openly contradicts the will of Christ, scandalizes the world, and damages the holy cause of preaching the Gospel to every creature.”
What Unites Us
§ 838 The Church knows that she is joined in many ways to the baptized who are honored by the name of Christian, but do not profess the Catholic faith in its entirety or have not preserved unity or communion under the successor of Peter. Those who believe in Christ and have been properly baptized are put in a certain, although imperfect, communion with the Catholic Church. With the Orthodox Churches, this communion is so profound that it lacks little to attain the fullness that would permit a common celebration of the Lord’s Eucharist.
§ 839 When she delves into her own mystery, the Church, the People of God in the New Covenant, discovers her link with the Jewish People, the first to hear the Word of God. The Jewish faith, unlike other non-Christian religions, is already a response to God’s revelation in the Old Covenant. To the Jews belong the sonship, the glory, the covenants, the giving of the law, the worship, and the promises; to them belong the patriarchs, and of their race, according to the flesh, is the Christ, for the gifts and the call of God are irrevocable.
§ 840 And when one considers the future, God’s People of the Old Covenant and the new People of God tend towards similar goals: expectation of the coming (or the return) of the Messiah. But one awaits the return of the Messiah who died and rose from the dead and is recognized as Lord and Son of God; the other awaits the coming of a Messiah, whose features remain hidden till the end of time; and the latter waiting is accompanied by the drama of not knowing or of misunderstanding Christ Jesus.
§ 841 The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind’s judge on the last day.
What Divides Us
During the two thousand years of Christian history we have seen four great separations. God’s people Israel during Rabbi Yeshua‘s time were torn when many Jews followed him but the Jewish authorities and many others did not follow. Islam during the seventh century refused to accept Rabbi Yeshua as the Son of God. The Orthodox during the eleventh century and the Protestants during the sixteenth have also become prodigal sons. In our own age God is calling them home.
Pope Benedict XVI, speaking in Cologne on August 19, 2005, to representatives of non-Catholic churches, said, “This unity does not mean what could be called ecumenism of the return: that is, to deny and to reject one’s own faith history. Absolutely not! It does not mean uniformity in all expressions of theology and spirituality, in liturgical forms and in disciplines.”
That sounds on the surface as if he is abandoning Catholic purity. But look closely! No pre-conciliar pope has ever insisted on uniformity in theology, spirituality, liturgical forms or discipline for returning movements.
The Church has always allowed theological differences among her Fathers and Doctors, she treasures her Augustinian and Thomist theologies, her Benedictine, Capuchin, Carmelite, Cistercian, Dominican, Franciscan, Jesuit and many more spiritualities, as she does her Holy Sacrifice of the Mass according to the missals of Popes Paul VI and Pius V and her Divine Liturgies in the Byzantine, Ruthenian, Chaldean, Maronite and other traditions, all of which returned to Rome after centuries of separation.
As to discipline, Canon law allows for considerable variation between particular and universal law. In fact, Holy Mother Church has two bodies of canon law, the Code of Canon Law, and the Code of Canons of the Eastern Churches. Notice that Pope Benedict XVI did not mention doctrine. Doctrine is God’s revelation to man, and therefore unchangeable by man.
Father Hardon on the Ecumenical Movement 5:11