Given the unique status of the Holocaust as an icon of evil in a morally confused world, Holocaust-denial triggers revulsions similar to those triggered by blasphemy in the Middle Ages: the Holocaust-denier must be shunned, for everyone else’s moral health. Thus it was completely understandable that, when Pope Benedict XVI lifted the excommunications of four bishops illegally ordained in 1988 by the late French archbishop Marcel Lefebvre, reporting and commentary focused on the fact that one of the four, Richard Williamson, is a Holocaust-denier and a man given to extolling that hoary anti-Semitic forgery, “The Protocols of the Elders of Zion.”

Understandable, but something of freakish sideshow, for Williamson is an internationally known crank and no serious person can believe that Benedict XVI’s act constituted an endorsement of Williamson’s lunatic view of history. As the pope made clear at his Jan. 28 general audience, he has long recognized the Holocaust as a unique icon of wickedness -- one that should call all of us “to reflect on the unpredictable power of evil when it conquers the heart of man.”

For Catholics, condemning Holocaust-denial is a moral imperative rooted in the conviction that anti-Semitism (of which Holocaust-denial is a pseudo-sophisticated form) is a sin against the God of Abraham, Isaac, Jacob, and Jesus -- a God who keeps his promises, both to the people of Israel and to the people of the Church. That conviction leads readily to another conviction: that God preserves the Church from fundamental error in essential truths. And that, not questions of liturgical taste, is what is really at issue with Lefebvrists: Were the Second Vatican Council’s teachings on the nature of the Church, on Church-state theory, and on the sin of anti-Semitism in continuity with the great tradition of Catholic faith? Or did they represent a rupture and a breach of faith?

The interpretation of Vatican II among Catholic “progressives” has long stressed that Vatican II was a Council of radical change: a new beginning that, in effect, created a new Church. On this understanding, the Council broke with hundreds of years of Catholic history by mandating an open dialogue with secular modernity. In an odd mirror-image, the Catholic far right -- embodied by Lefebvrists, among others -- agrees: except that, in this instance, rupture means betrayal. Marcel Lefebvre was shaped in part by currents in French public culture that helped produce the Vichy regime during World War II. To a mind formed in that cauldron of resentments, prejudices, and dreams of an ancient regime restored, it seemed self-evidently clear that the Council made a fatal bargain with modernity, thereby emptying Catholicism of its content while eviscerating the distinctive Catholic way of life.

For the past three decades, by contrast, Joseph Ratzinger has argued vigorously in defense of Vatican II as an authentic expression of Catholic faith that must be interpreted in continuity with the Church’s tradition. For Ratzinger, Vatican II was a Council of development: its teaching teased new meanings out of ancient tradition, but it in no way involved a rupture with the past. How could it, if God keeps his promise to preserve the Church in essential truths?

The Council’s continuity with the great tradition of Catholic faith is what Archbishop Lefebvre and his movement have long denied. And while some may sympathize with the Lefebvrists’ commitment to dignified worship, few, I suspect, will want to defend the Lefebvrist claim that the Council taught falsely when it defined religious freedom as a fundamental human right.

Thus if Benedict XVI’s attempt to reconcile dissidents on the far starboard edge of world Catholicism is to contribute to the Church’s unity, his gestures of reconciliation must be met from the Lefebvrist side by a clear rejection of the rupture theory of Vatican II. That means an unambiguous acknowledgment from the Lefebvrist bishops that the Council taught the truth of Catholic faith in affirming religious freedom and condemning anti-Semitism. Until that happens, the absurd Lefebvrist claim that their movement is “the Tradition” (most recently made by the leading Lefebvrist bishop, Bernard Fellay) will remain an insuperable obstacle to the restoration of full communion.

George Weigel is Distinguished Senior Fellow of the Ethics and Public Policy Center in Washington, D.C.