How many in mainline? Categories vary in surveys: Defining the mainline

Americans who identify with mainline churches make up either 18 percent of the U.S. population or 13 percent, according to two large-scale surveys taken within recent years. Which is right?

Both are, say some researchers. The statistical variations typically depend on what questions are asked and how the mainline is defined.

Few doubt that the graying of members, low birth rates and various controversies have contributed to the diminishing numbers of mainline Protestants found in the United Methodist Church, the Evan gelical Luth eran Church in America, the Pres byterian Church (U.S.A.), the Epis copal Church, the American Baptist Churches and the United Church of Christ.

But has the slippage become precipitous, threatening to reduce mainline Protestants ever closer to remnant status? “A generic form of evangelicalism is emerging as the normative form of non-Catholic Christianity in the United States,” said Mark Silk, who helped design the 2008 American Religious Identification Survey (ARIS).

That survey, which polled more than 54,000 adults, reported in March that the number of mainline Christians had slipped to 12.9 percent of adult Americans—down from 17.2 percent in 2001 and 18.7 percent in 1990—as evangelical numbers grew.

By contrast, the Pew Forum’s U.S. Religious Landscape Study, after polling 35,000 adults in 2007, reported last year that 18.1 percent of adults said they were affiliated with “mainline Protestant” churches.

Asked about this 5 percent difference, senior fellow John C. Green of the Pew Forum on Religion & Public Life said, “It isn’t that our numbers are more right than [ARIS’s] numbers . . . but how one conceptualizes the group.”

Pew Forum’s Religious Landscape survey counted all respondents affiliated with the historical mainline denominations and all members of relatively small denominations not always grouped by pollsters in the mainline category. These include the Quakers, the Reformed Church in America, the Church of the Brethren, the Cooperative Baptist Fellowship and the Metropolitan Com munity Church.

The Pew survey also included in its mainline figures some respondents who simply identified themselves as Prot estant or said they were members of nondenominational or independent churches. One way to determine whether to consider such respondents mainliners, Green said, was to ask them if they were “born again” or not. These additional respondents accounted for nearly one-fifth of Pew’s total for mainline Protestants.

“Non–born-again folk in these kinds of churches look very much like members of specific mainline denominations in terms of religious beliefs and behaviors,” Green said in an e-mail interview. Some errors may appear, he said, but he believes that larger errors occur when nondenominational community churches are simply classified separately.

The ARIS category of mainline Christians contained most historical mainline Protestants but excluded liberal-to-moderate Baptists, peace church affiliates and independent/nondenom inational church members with mainline perspectives. The latter fell into ARIS’s “Christian generic” classification, which is populated heavily with evangelicals.

In announcing the ARIS findings, researchers at Trinity College in Hart ford, Connecticut, said that “most of the growth in the Christian population occurred among those who would identify only as ‘Christian,’ ‘Evangelical/Born Again,’ or ‘nondenominational Christian.’”

Evangelical Christians account for 34 percent in the ARIS study, whereas Pew’s landscape survey puts them at 28.3 percent. Thus Pew’s figures show a gap of 10 percentage points between mainliners and evangelicals, compared to ARIS’s 20-point spread.

“It looks like the two-party system of American Protestantism—mainline versus evangelical—is collapsing,” said Silk, director of Trinity College’s Public Values Program. Sociologists Barry Kosmin and Ariela Keysar coauthored the 2008 ARIS study.

The ARIS data and a recent Newsweek cover story on the “decline” of Christian America prompted Christianity Today to post an unsigned article in its online edition March 12. The “real story,” the article said, is that the American church “is becoming more conservative and evangelical, though somewhat less denominational.” And, it added, “for good and for ill . . . evangelicals nationwide are becoming the new mainline.”

One prominent sociologist of religion declared that the Pew and ARIS findings are not groundbreaking. Mark Chaves, who teaches at Duke University, said in an e-mail interview that the percentage of the population identifying with the mainline has been “declining for decades. I think it’s kind of beside the point to ask whether it’s really 18 or 13 percent.”

Chaves described the General Social Survey as a good measuring stick: “GSS gets 13.6 percent for mainline in 2008 and 28.1 percent for evangelical, which is qualitatively similar to both Pew and ARIS.” Admitting his partiality—he chairs the GSS board of overseers—Chaves noted that this Chicago-based survey is the “gold standard” in polling because it does in-person interviews and has been tracking religious trends since 1972.

Tom W. Smith, director of the GSS, said, “We ask what denomination people belong to” and then place the respondents into larger groups like Pentecostal, mainline, black and evangelical. The Pew landscape survey finds more mainline adherents among respondents who give vague responses. “Green’s definition of mainline seems broader than most I’ve seen,” Smith said.

The differences in defining mainline Protestants in polls do account for different totals, agreed Robert P. Jones, president of Public Religion Research. “The short answer is that both [Pew and ARIS] numbers are correct.”

But Jones indicated that a broad view of mainline traditions, when sustained in oldline denominations and within new nondenominational churches, is important for a healthy civil society. “The mainline remains one of the few places in our increasingly polarized . . . society where people with disparate opinions and beliefs continue to rub shoulders on a regular basis,” he said.