Just before he led the cardinals into sequester in the Sistine Chapel on Monday, Cardinal Joseph Ratzinger laid down the theological gauntlet, calling upon the church to wield Jesus Christ as a shield against a "dictatorship of relativism." He depicted the church as a "little boat of Christian thought" tossed by waves of "extreme" schools of modern thought, identified as Marxism, liberalism, libertinism, collectivism and "radical individualism."

Two days later, he emerged Pope Benedict XVI--and that term, relativism, suddenly became an important key to understanding the direction the new pope will take his church. So what does it mean?

In a nutshell, relativism (or moral relativism-they're often used interchangeably), is the idea that moral principles are based on your culture (such as where and when you live, your education, your age, and your level of wealth) and therefore subject to individual choice. Taken to an extreme, a moral relativist believes there are no rules governing right and wrong. So, for example, when certain sectors of African society permit polygamy, some thinkers say that practice is acceptable because it arises from that particular culture-making it moral in "relative" circumstances.

But people who oppose moral relativism say that unless global society clearly defines right and wrong--for instance, prohibiting polygamy, or for that matter, gay marriage--we head down a treacherous path. You will often hear opponents of gay marriage say that if we permit that, what stops society ultimately from permitting bestiality. This is why those who wring their hands over "moral relativism" also often say that by not stopping Janet Jackson "wardrobe malfunctions," society has inevitably allowed itself to slide into pornography, premarital sex, abortion-on-demand, and assisted suicide.

Americans have heard the term because evangelical Christians, including President Bush, often use it to describe their view of American culture. In fact, when Bush returned from Pope John Paul II's funeral, he had this to say: "I would define Pope John Paul II as a clear thinker who was like a rock," he said "Tides of moral relativism kind of washed around him, but he stood strong."

Dr. James Dobson of Focus on the Family talks frequently about the concept. In a 1998 <"http: www.wildershow.com/dobson.htm"="" target="_new" "="">speech, he talked about the fears of his audience: "I know their heart. I read their letters. I talk to them on the telephone. They love their God and they are very, very concerned about what's happening today. They see this moral freefall. They see this moral relativism and they're very concerned about it. It contradicts everything they stand for and they also feel under attack. They feel under assault by Hollywood and they can't do anything about it and by the rock music industry that just sells sex and violence and all sorts of evil to their kids..They feel the culture has got their families."

Dobson, Pope Benedict XVI, and others who oppose relativism say that modern society, especially in North America and Europe, is filled with the influences of evil--and that evil must be actively battled. Christianity, they say, is the only possible victor.

Evangelicals tend to see Christian belief and practice as a method for avoiding evil and immorality--that's what Bush means when he says John Paul II stood against moral relativism. But Pope Benedict means something slightly different and perhaps deeper. He is most worried about relativism arising from pluralism, the idea that other religions are valid ways of searching for meaning.

"He thinks relativism is something that happens when people live in pluralism," says William Portier, a theologian at the University of Dayton who specializes in Catholic intellectual thought. "It's like an occupational hazard-you begin to think in this way because you have to live with all these different people."

Portier says he sees this "occupational hazard" all the time among his students. "They don't want to say that someone else is wrong," says Portier, who has taught for more than 30 years. "It's because they live in this incredibly chaotic, pluralistic, fragmented world. And they don't want anybody to say they're wrong either."

The "problem of relativism" is especially resonant among U.S. Catholics, Portier says. Here, as well as in parts of Europe, Catholicism created its own subculture-which is now largely dismantled as a result of pluralism. "My students don't come from Catholic grammar schools where they were taught by nuns," Portier says. "So people do live in pluralism. And pluralism affects how you think, so if you want to be a [Catholic] believer in the midst of pluralism, you have to correct for that thinking."