The ecumenical quest for Christian unity is not, and cannot be allowed to become, an ecclesiastical form of political correctness. Ecumenism does not mean that differences make no difference. Rather, true ecumenism is the mutual search for the truth - the truth that Christians believe Christ bequeathed to his church as an enduring gift. The mutual search for the one truth of Christ is impeded, not advanced, when it's assumed that doctrinal and liturgical differences, and differences in moral conviction, are not important.

Ignoring differences as if differences didn't matter is not tolerance. Real tolerance means engaging differences within the bond of civility and respect. That was the kind of ecumenism pioneered by Cardinal Lawrence Shehan when he established the Catholic Church's first diocesan ecumenical commission in Baltimore -- an ecumenism of differences engaged, with charity and respect, not a false ecumenism of differences ignored or swept under the ecclesial rug.

That is the kind of ecumenism to which the Catholic Church has been committed since the Second Vatican Council. It's not an ecumenism that can be summarized in that famous lament, "Why can't we all just get along?" We can certainly all "get along" as fellow Christians, recognizing our bond in Christ and committed to the Church's unity. But unless "getting along" means wrestling with our different understandings of the truth of Christ, we risk reducing ecumenism to a hollow kind of flattery, in which all we do is tell each other what decent folks we are.

Two popes -- Paul VI and John Paul II -- frequently spoke of how deeply they wished they could have concelebrated the Eucharist with the ecumenical patriarch of Constantinople, the leading figure of world Orthodoxy; both popes ultimately decided that any such concelebration, prior to agreement on key issues of doctrine and church governance, would be a false sign, a kind of "cheap grace."

To be sure, this acknowledgment of differences hurts, personally and spiritually. But perhaps if we felt the pain of division in the Church more acutely, our efforts to recompose the unity that was fractured in the second millennium of Christian history would take on greater urgency. Perhaps the ecumenical search for truth would rise in our priorities.

The Catholic Church believes, as Vatican II put it, that there are many elements of sanctification in other Christian communities. At the same time, the Catholic Church believes that it is the fullest expression in history of Christ's intention for what his Church should be. Is that conviction an impediment to ecumenical dialogue? I don't think so, and a story from a related arena makes the point.

When Pope John Paul II was in Jerusalem in 2000, several Jewish leaders suggested that he not wear his cross when he prayed at the Western Wall of the Temple, Judaism's holiest place. I was working with NBC at the time and asked a friend, a rabbi, what he thought about these agitations. His response was simple, direct, and right on the mark: "Genuine inter-religious dialogue begins with taking the other for who he is."

That truth of inter-religious dialogue holds for Christian ecumenical dialogue, too. Catholicism's dialogue partners cannot begin by asking the Catholic Church to be something that it isn't. The serious dialogue partners understand that.

-- George Weigel, distinguished senior fellow of the Ethics and Public Policy Center in Washington, is a native of Baltimore. His e-mail is gsweigel@aol.com.