A new survey on American religion finds that the percentage of Christians has stabilized, after having fallen for the past 20 years. The survey, called The 2020 Census of American Religion, claims that the recent increase is primarily due to an uptick in the proportion of white mainline Protestants.

But just as “evangelical” has become a synonym in the public mind with “conservative white Protestants,” this survey shows that “mainline” has come to mean “non-evangelical Protestant.” (All respondents who identified as Christian were asked: “Would you describe yourself as a ‘born again’ or ‘evangelical Christian,’ or not?” Respondents who self-identified as white, non-Hispanic, or Protestant and affirmatively identified as born-again or evangelical were categorized as white evangelical Protestants.)

Defining Our Terms

Who exactly are mainline Protestants? Here is what you should know about the faith tradition that once dominated the American religious landscape.

1. No one knows for sure where the label “mainline” comes from.

The origin of “mainline” is uncertain. A common assumption is that it came from the formation of the Federal Council of Churches in 1908, which was located along the Philadelphia Main Line, a group of affluent suburbs of Philadelphia. During the 1920s, the term gained in popularity in identifying American churchgoers who tended to side with the modernists in the Fundamentalist-Modernist controversy.

2. The “seven sisters of American Protestantism” are the major mainline denominations . . .

In 1989, William Hutchison coined the term “seven sisters of American Protestantism” to refer to seven major denominations that comprise the mainline: American Baptist Churches USA, the Christian Church (Disciples of Christ), the Episcopal Church, the Evangelical Lutheran Church in America, the Presbyterian Church (USA), the United Church of Christ, and the United Methodist Church.

3. . . . But the term is often applied to dozens of smaller denominations.

What constitutes a mainline denomination is unclear. Generally, the term is applied to groups that are not explicitly evangelical or fundamentalist. Other denominations often included as mainline churches are the Alliance of Baptists, Church of the Brethren, the Congregational Christian Churches (not part of any national CCC body), Cooperative Baptist Fellowship, the Mennonite Church, the Moravian Church in North America, the Reformed Church in America, and the Religious Society of Friends (Quakers).

4. Mainline denominations are theologically pluralistic.

From the perspective of evangelicalism, mainline denominations are often considered “liberal.” But a more fair and accurate categorization would be that they have embraced theological pluralism. Like the other two major Christian traditions in America—evangelicalism and Roman Catholicism—mainline Protestantism includes a diversity of theological perspectives, ranging from conservative to radical. For example, a 2008 Pew survey asked if the Bible was the Word of God. About one-in-four (24 percent) mainline Protestants said it was the Word of God and should be taken literally, while a roughly equal number (28 percent) said it was not the Word of God.

5. Mainline schisms gave birth to several evangelical denominations.

The pluralism of mainline denominations often causes a rift among the more conservative factions. For example, disagreements in the mainline Presybeterian denominations led to the creation of the Orthodox Presbyterian Church in 1936, the Presbyterian Church in America in 1973, and the Evangelical Presbyterian Church in 1981. More recently, a group of leaders within the United Methodist Church unveiled a proposal last year that would allow the denomination to split into two or more new denominations, representing the conservative or “traditionalist” faction and the LGBT-affirming factions.

6. Mainline Protestants are about as equally Republican as Democrat.

Mainline denominations are often associated with the Democratic Party and progressive social causes. But in the pews, most mainliners are about evenly split between Democrats and Republicans. In only four denominations do Democrats comprise a slim majority of the denomination: American Baptist Churches USA, Disciples of Christ, the Episcopal Church, and the United Church of Christ. In contrast, the other three are closer to the GOP. The United Methodist Church, which is the second-largest Protestant denomination in the United States, is 53.7 percent Republican and only 35.1 percent Democratic, while the Disciples of Christ is 52.8 percent and the PCUSA is 49.9 percent. As Ryan P. Burge notes, “[T]he best way to describe mainline Protestantism’s politics today or [40] years ago is slightly to the right of center. It would be a mistake to ever identify them as Democrats, although it would be more appropriate to say that many were moderate Republicans.”

7. Most mainline Protestants live in the Midwest.

According to the new PRRI survey (remember the preceding caveats), white mainline Protestants are spread around the country but are most heavily concentrated in counties in the Midwest. The 10 highest concentrations of white mainline Protestants in counties with more than 10,000 residents are:

  • Pope County, Minnesota (37%)
  • Chippewa County, Minnesota (37%)
  • Stutsman County, North Dakota (35%)
  • Clayton County, Iowa (35%)
  • Dunn County, Wisconsin (35%)
  • O’Brien County, Iowa (34%)
  • Faribault County, Minnesota (34%)
  • Otter Tail County, Minnesota (34%)
  • Fillmore County, Minnesota (34%)
  • Mille Lacs County, Minnesota (34%)

The median age of white mainline Protestant adults is 50. This is older than the median age of all Americans (47), but somewhat younger than the median age of all white Christians (53).

8. Mainline denominations (still) dominate in the three branches of the federal government.

Since the 1900s, many U.S. Presidents have come from mainline denominations, including President George W. Bush, who was a member of a United Methodist church, President Barack Obama, who was baptized in the United Church of Christ, and President Donald Trump, who was originally affiliated with the Presbyterian Church (USA) when he was elected. Historically, most Supreme Court justices also came from a mainline denominations (they have included 33 Episcopalians, 18 Presbyterians, nine Unitarians, five Methodists, three Baptists, and two Disciples of Christ). In the 1990s, four of the U.S. Supreme Court Justices were mainline Protestants: Sandra Day O’Connor, William Rehnquist, David Souter, and John Paul Stevens. Now Justice Neil Gorsuch, an Episcopalian, is the only mainline Protestant denomination on the court. About half of the members of Congress are affiliated with mainline churches.

9. The mainline population has been declining for more than five decades.

In the middle of the 20th century, the majority of Americans identified as mainline Protestants. But as Pew Research pointed out in 2015, the most pronounced changes have occurred in churches in the mainline Protestant tradition, with the share of adults belonging to mainline churches dropping from 18.1 percent in 2007 to 14.7 percent in 2014. If we look back more than 50 years (to 1965) we can see a clear and unequivocal trendline of sharp decline. For example, in 1966, the Episcopal Church had 3,647,297 members; by 2013, the membership was 1,866,758, a decline of 49 percent. Similarly, in 1965, the Christian Church (Disciples of Christ) had 1,918,471 members. In 2012, the membership was 625,252, a decline of 67 percent. Every one of the “seven sisters” has seen long-term decline in membership.