The mainline Protestant churches (also called mainstream Protestant and sometimes oldline Protestant) are a group of Protestant denominations in the United States that contrast in history and practice with evangelical, fundamentalist, and charismatic Protestant denominations. Some make a distinction between "mainline" and "oldline", with the former referring only to denominational ties and the latter referring to church lineage, prestige and influence. However, this distinction has largely been lost to history and the terms are now nearly synonymous.
Mainline Protestants were a majority of Protestants in the United States until the mid-20th century. A dip in membership across all Christian denominations was more pronounced among mainline groups, with the result that mainline groups no longer comprise the majority. In 2020, Public Religion Research Institute conducted a religious census, based on self-identification, finding that an estimated 16% of U.S. Americans identified as non-Hispanic white mainline Protestants, slightly outnumbering non-Hispanic white evangelical Protestants who were 14% of the US American population. In 2014, Pew Research completed and published the Religious Landscape Survey in which it was estimated that 14.7% of US Americans identified as mainline Protestant, excluding historically Black and African American denominations, while 25.4% identified as evangelical Protestants, also excluding membership in historically Black denominations.
Mainline churches include the so-called "Seven Sisters of American Protestantism":
- United Methodist Church
- Evangelical Lutheran Church in America
- Presbyterian Church (USA)
- The Episcopal Church
- American Baptist Churches
- United Church of Christ
- Disciples of Christ
Also included in the mainline are:
The term 'mainline' has also been applied to Canadian Protestant churches that share common origins with their US counterparts. In Mexico, the Anglican Church is historically tied to and formed from the US Episcopal Church. The term is also occasionally used to refer to historic Protestant churches in Europe, Latin America, and South Africa.
Mainline churches share an active approach to social issues that often leads to cooperation in organizations such as the National Council of Churches. Because of their involvement with the ecumenical movement, mainline churches are sometimes (especially outside the United States) given the alternative label of ecumenical Protestantism. These churches played a leading role in the Social Gospel movement and were active in social causes such as the civil rights movement and the women's movement. As a group, the mainline churches have maintained religious doctrine that stresses social justice and personal salvation. Members of mainline denominations have played leadership roles in politics, business, science, the arts, and education. They were involved in the founding of leading institutes of higher education. Marsden argues that in the 1950s, "Mainline Protestant leaders were part of the liberal-moderate cultural mainstream, and their leading spokespersons were respected participants in the national conversation."
Some mainline Protestant denominations have the highest proportion of graduate and post-graduate degrees of any other denomination in the United States. Some also include the highest proportion of those with some college education, such as the Episcopal Church (76%), the Presbyterian Church (U.S.A.) (64%), and the United Church of Christ (46%), as well as the most of the American upper class. compared with the nationwide average of 50%. Episcopalians and Presbyterians also tend to be considerably wealthier and better educated than most other religious groups, and they were disproportionately represented in the upper reaches of US business and law until the 1950s.
From 1854 until at least 1964, Mainline Protestants and their descendants were heavily Republican. In recent decades, Republicans slightly outnumber Democrats.
From 1965 to 1988, mainline church membership declined from 31 million to 25 million, then fell to 21 million in 2005. While in 1970 the mainline churches claimed most Protestants and more than 30 percent of the population as members, today they are a minority among Protestants; in 2009, only 15 percent of Americans were adherents. A Pew Forum statistic revealed the same share in 2014.