Since the pilgrims landed at Plymouth Rock nearly 400 years ago, America has been a largely Protestant nation.

But as early as the end of this year, Protestants likely will make up less than 51 percent of the population for the first time in history, sociologists at the university's National Opinion Research Center surmise in a new report released Tuesday.

According to survey results from more than 43,000 Americans gathered over the last 30 years, the percentage of Protestants in the national population has shrunk from 63 percent in 1993 to 52 percent in 2002.

Surveys defined Protestant as any Christian denomination that was formed at the time of the Reformation or thereafter, including groups such as the Church of Jesus Christ of Latter-day Saints, said Tom Smith, director of the NORC's General Social Survey, where most of the data was collected.

"Our projection is that the Protestant percentage in the 2004 survey will probably be somewhere between 50 and 51 percent," Smith said. "It's particularly striking because for 30 years, it was absolutely stable.''

Smith said media have covered "the rise of nontraditional American religions ... and the rise of people without any faith, but what was missing from that story was, OK, the number of people with no faith was rising but nobody was paying attention to where they were coming from."

In the last 30 years, the number of people who say they were brought up with no religion at all has risen from 2 percent to 7 percent, according to the NORC report.

From 1993 to 2002, the number of people who said they had no religion rose from 9 percent to nearly 14 percent, and in that same time period the number of people who said they were raised Protestant fell from 64 percent to about 56 percent.

"There is some evidence that a large portion of this problem is that a fair number of marginal Protestants are not really engaged in their faith and therefore didn't pass it on to their kids," Smith said. "The mom and dad would say, for example, 'Yeah, we're Methodists,' but they never went to church. They'd baptize their kids and that's about it."

If the Protestant majority does indeed disappear, the United States will be a nation of religious minorities. The next largest religious group after Protestant is Roman Catholic, at about 25 percent. The Catholic population has remained stable over the last decade, according to the NORC study.

"The Catholic defection is [also] pretty large, but they are being replaced by immigrants," said R. Stephen Warner, a professor of sociology at the University of Illinois at Chicago, after reviewing the NORC report. "Christianity is becoming a religion of people of color. Part of this is the decline of the WASP."

The Rev. John Buchanan, pastor of Chicago's 5,200-member Fourth Presbyterian Church, said he welcomes the demise of the Protestant majority.

"I'm not applauding the Protestant decline . . . what I'm applauding is the viability of a truly diverse nation, a nation that opens its arms and heart to different races, different religions," said Buchanan, whose own congregation is bucking trends by doubling its attendance in the last decade.

"I think that's a better place to be than a nation that's dominated by one religion -- whatever it is."