Protestants have become the new American minority.

According to the latest number crunching at the National Opinion Research Center, the number of Americans who say they are Baptist, Methodist, Lutheran, Presbyterian, Evangelical or other varieties of Protestantism dropped from 63 percent in 1993 to 52 percent in 2002.

Now, assuming that trend continued, the old Protestant establishment has already become the latest minority group in an increasingly diverse U.S. population.

Tom W. Smith, the principal author of the new study on "The Vanishing Protestant Majority," cites several reasons for this seemingly sudden shift in the American religious landscape, including rising numbers of immigrants from Catholic and non-Christian cultures.

But the main reason lies in the answers younger Americans offer when pollsters ask them their religious denomination, according to Smith.

People who used to be nominally Protestants and hardly ever go to church would still give answers like "Methodist" or "Protestant."

Today, their children or even they are more likely to say "no religion" or "huh?" when asked about their denominational loyalties.

Smith's study, which was released Tuesday, follows an earlier analysis of these same data that reported a doubling in the number of people who say they have "no religion."

They are the so-called "nones," people who may still believe in God or an afterlife but fall into the "none-of-the-above" category.

"What we weren't paying attention to before is the fact that these 'nones' had to come from somewhere,'' Smith said in an interview with The Chronicle on Tuesday. "They are coming from the Protestant churches.''

Protestants contacted Tuesday by The Chronicle reacted with neither surprise nor dismay.

"Plenty of us are alive and well,'' said the Rev. Jim Burklo, the pastor at Sausalito Presbyterian Church, which still finds from 70 to 80 people sitting in its pews on a typical Sunday.

Burklo said there was absolutely no question that "denominational identity is slipping" among younger Americans -- a trend that has been documented in many books over the last decade.

For nine years, Burklo served as a campus minister at Stanford University, where incoming first-year students from across the nation and around the world are asked to fill out little cards that say what kind of church, synagogue, temple or mosque they might wish to attend.

"Every year," he said, "it got more complicated trying to figure out where to send those cards.''

Meanwhile, officials at the Manhattan-based National Council of Churches, a longtime bastion of American Protestantism, appeared unflustered by the latest news of their decline.

"We don't worry about it," said Pat Pattillo, the director of communications for the Protestant and Orthodox Christian ecumenical agency that still counts nearly 50 million members in its member denominations.

"Mainline Protestants have always been very involved in American life," Pattillo said, "and are still very active."

Protestants have long been seen by many to embody the American majority establishment.

However, as Pattillo pointed out, there has long been disagreement as to who to include in that category.

"If you narrowly define 'Protestant,' we have never been a majority," said Pattillo, a Baptist.

Smith's study includes in the "Protestant'' camp all post-Reformation Christian groups -- including fast-growing movements like the Mormon church, Pentecostalism and the Jehovah's Witnesses.

"Those are the groups that have helped keep the Protestant numbers up,'' he said.

Nominal Catholics who rarely go to church or don't adhere to Catholic teaching, Smith said, are less likely to stop calling themselves "Catholic" because religion tends to be more of a part of their "core identity" as Italians, Irish, Poles, Filipinos, Latinos or people from other Catholic homelands.

Smith is the director of the National Opinion Research Center's General Social Survey, which unlike the U.S. Census, has been tracking the religious identification of Americans for more than three decades.

Data collected from the center, located at the University of Chicago, are used by many social scientists in their study of American attitudes and behavior.