The words broke like a thunderclap inside St. Peter's Basilica. Cardinal Joseph Ratzinger, addressing the world's cardinals just hours before they sequestered themselves Monday to choose the next leader of the world's 1 billion Catholics, decided to define this conclave.

"We are moving," he declared, toward "a dictatorship of relativism . . . that recognizes nothing definite and leaves only one's own ego and one's own desires as the final measure."

The modern world, Ratzinger insisted, has jumped "from one extreme to the other: from Marxism to liberalism, up to libertinism; from collectivism to radical individualism; from atheism to a vague religious mysticism; from agnosticism to syncretism and on and on."

Those are fighting words. They guaranteed that Ratzinger, who was Pope John Paul II's enforcer of orthodoxy, will either set the church's course -- or offer his fellow cardinals the ideas they choose to react against. Decades from now many conservative Catholics will see the war against the "dictatorship of relativism" as their central mission. It's not a line you forget.

What makes this papal election so unusual is not the normal disagreement over specific issues. The odd part is that the cardinals disagree fundamentally over what the election is really about because they differ in their judgments of what are the most important issues confronting the church.

Ratzinger, who is German, spoke for the conservative side of a culture-war argument that is of primary interest to Europe and North America. When Ratzinger said on Monday that "to have a clear faith according to the church's creed is today often labeled fundamentalism," his words were undoubtedly welcomed by religious conservatives far outside the ranks of the Catholic Church. One can also imagine that liberals of various stripes shuddered.

But for the many cardinals here from the Third World -- 20 of the 115 voting are from Latin America, 11 from Africa, 10 from Asia -- the battle over relativism is far less important than the poverty that afflicts so many of their flock. Some of these cardinals -- Claudio Hummes of Brazil is a representative figure -- may share points in common with Ratzinger on doctrine. But for them the struggle against suffering and social injustice is part of their lives every single day.

Many of these same cardinals, and some in Europe and the United States, place a higher priority on Christianity's rekindled competition with Islam and the urgency of Muslim-Christian dialogue. It's not clear where Ratzinger's approach would take these efforts.

Ratzinger, in other words, is now central to two very different dynamics inside the conclave. Cardinals will be asked to decide -- by voting for or against him or someone he favors -- whether Ratzinger's theological approach is right. And they will decide whether Ratzinger's priorities involve the things that matter.

It makes perfect sense that Ratzinger would be the decisive player in defining the church after the papacy of John Paul II. Joaquin Navarro-Valls, the Vatican spokesman, once said that John Paul's choice of Ratzinger as his doctrinal chief was "one of the most personal choices of his pontificate."

Ratzinger is a brilliant, tough-minded intellectual who started out as moderately liberal and -- like so many American neoconservatives -- developed a mistrust of the left because of the student revolt of the 1960s. He once said that "the 1968 revolution" turned into "a radical attack on human freedom and dignity, a deep threat to all that is human." The pope knew what he was getting with Ratzinger, and he got what he wanted.

With Ratzinger playing the tough cop against dissent, John Paul was free to be more expansive. Rocco Buttiglione, a philosopher who was close to the late pope, captured their division of labor perfectly in an interview some years ago. "The pope has more the gift of synthesis, because of his office," Buttiglione said. "Cardinal Ratzinger has more the gift of polemic."

There was also the matter of their personalities. Where John Paul was sunny, Ratzinger was serious -- and a worrier. Walls in Rome are plastered with memorial posters to John Paul that carry his famous quotation, "Be not afraid." Cardinal Ratzinger declared yesterday that the church has much to fear.

Ratzinger now carries on his battle without the charismatic support of his friend. He is proposing that the church take one aspect of John Paul's synthesis -- the battle against relativism reflected in doctrinal rigor -- and make it the late pope's central legacy. The cardinals who marched solemnly into the Sistine Chapel yesterday afternoon will be deciding if that is the right fight for the future.