Next Sunday, Jan. 18, marks the start of the annual Week of Prayer for Christian Unity. For Catholics, the commemoration comes at the end of a year of disappointments in ecumenism.

But Father James Massa, the executive director of the Secretariat for Ecumenical and Interreligious Affairs of the U.S. Conference of Catholic Bishops, sees new opportunities, too. In an e-mail interview, which we excerpt here, he identifies this year's highs and lows, and the work that remains to be done.

Our Sunday Visitor: The turmoil within the Anglican Communion over the ordination of an openly homosexual bishop has caused great ecumenical concern. How has it affected the Anglican-Catholic dialogue?

Father James Massa: It is a cause of great sadness for the Catholic Church when any of her partners decides to endorse a moral position that clearly departs from traditional Christian morality. Since the ordination of Gene Robinson as a bishop of the Episcopal Church, we Catholics have watched the Anglican Communion struggle to maintain its bonds of unity. Other ecclesial communities, such as the Evangelical Lutheran Church in America, may be considering a change in practice with respect to ordaining openly homosexual candidates and blessing same sex unions. Every move in this direction makes the goal of full communion more and more distant in the journey of Christian unity.

In a not-so-subtle way, Pope Benedict XVI expressed his own deep concern at the ecumenical service in New York City last April 18 about those churches that have adopted "local options" that depart from biblically based moral principles. I cannot help but see a certain irony in the fact that the pope is exhorting Protestants and Anglicans to be faithful to Scripture, which is precisely what these partners of ours have, on so many past occasions, exhorted us to do in addressing other doctrinal matters.

OSV: Protestant churches lack a magisterium. Is this a source of frustration from the Catholic perspective, or does it serve as a catalyst for discussing the very issue of Church authority?

Father Massa: You touch on one of the fault lines in the divisions within Western Christianity. Can the Reformation principle of sola scriptura ["Scripture alone"] finally be sustained? The very same Lutherans and Anglicans who are locked in a heated debate over human sexuality appeal to the same body of Scripture to make their respective arguments.

This discussion, along with so many others, raises the question of whether Scripture requires the mediation of another authoritative agent. Some Christians recognize the role of Tradition -- the teachings of early councils, great theologians, the liturgy, etc. -- as the framework for interpreting Scripture. But even Tradition can be read through various lenses. Today both the Bible and Tradition are examined with the aid of historical critical methods of interpretation, which further complicates matters.

So, as you can see, our ecumenical partners are in a real muddle. Something like a living, authoritative voice is needed as the ultimate court of appeal when Christians are threatened with disunity over fundamental belief and practice. Otherwise, the communion of Christian believers disintegrates. Now this voice, which we Catholics believe to be the magisterium of bishops teaching in union with the pope, is itself bound to the word of God as attested in Scripture and Tradition. Popes and other bishops are its servants, not its masters. When it comes to something like the ordination of women, the pope and the entire worldwide episcopate cannot override what is believed to be the authoritative witness of Scripture and Tradition.

OSV: Is substantive Christian unity truly attainable, or is it a futile goal which we nonetheless are obliged to strive for because it is the stated will of Christ?

Father Massa: There is really only one option: to do everything, within our particular callings and capabilities, to answer the prayer of Christ in John 17: "Father, may they be one as we are one, so that the world may believe." The whole mission of the Church is packed into that final prayer of Jesus at the Last Supper, and it's a mission that contains both the summons to proclaim Christ as the one savior of all and the requirement that we enter into respectful dialogue with all people and all religions. There can be no competition between dialogue and proclamation. Both are essential components.

Like many others in the field of ecumenism, I get asked by fellow priests and lay colleagues: Why don't we just invite the other Christians to return home to the Catholic Church? My question to those who pose this question is this: Would we be any different if these, our Christian brothers and sisters in Christ, entered into full communion with the Catholic Church? Would we be impacted by the charismatic gifts of Pentecostal Christians who had now entered full communion with us? By the devotion to the Divine Liturgy and to sacred images of Orthodox Christians? By the faithfulness to the word of God of evangelicals and historic Protestants? In other words, the hoped-for attainment of Christian unity involves mutual conversion and the transformation of all us who would now profess the faith in common.

Of course, we Catholics have our own gifts to share. The Petrine ministry of the Bishop of Rome is a tremendous blessing, as is our filial devotion to the Blessed Virgin Mary, the first in the Communion of Saints. But our greatest treasure is the Eucharist celebrated in Catholic worship, the source and summit of all that we are as believers. Deep down, every Catholic who receives the holy Eucharist with an awareness of the love that the Real Presence and liturgical offering mediates wants desperately to share it with the whole world. That is the dream of Catholic ecumenism: one Lord, one faith, one Baptism, and one Eucharist.

Gerald Korson writes from Indiana.