Mainline Protestants (also referred to as modernist Protestants or oldline Protestants) are a group of historically established Protestant denominations in the United States and Canada that are generally associated with theologically liberal or theologically progressive currents of Protestantism, in contrast to the largely theologically conservative evangelical, fundamentalist, charismatic, confessional Confessing Movement, historically Black church, and Global South Protestant denominations and congregations. 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 Protestant churches have stressed social justice and personal salvation and, both politically and theologically, tend to be more liberal than non-Mainline Protestant churches. Mainline Protestant churches share a common approach that often leads to collaboration in organizations such as the National Council of Churches, and because of their involvement with the ecumenical movement, they are sometimes given the alternative label of ecumenical Protestantism (especially outside the United States). While in 1970 the Mainline Protestant churches claimed most Protestants and more than 30 percent of the American population as members, they were a minority among American Protestants, claiming approximately 15 percent of American adults. In 2025, approximately 13 percent of Americans were white non-Hispanic Mainline Protestants according to the Public Religion Research Institute's Census of American Religion.
Mainline Protestantism is largely associated with the "Seven Sisters of American Protestantism," those being the United Methodist Church, the Evangelical Lutheran Church in America, the Episcopal Church, the Presbyterian Church (USA), American Baptist Churches USA, the United Church of Christ, and the Christian Church (Disciples of Christ).
Terminology The term Mainline Protestant was coined during debates between modernists and fundamentalists in the 1920s. Several sources claim that the term is derived from the Philadelphia Main Line, a group of affluent suburbs of Philadelphia; most residents belonged to Mainline denominations. Today, most Mainline Protestants remain rooted in the Northeastern and Midwestern United States. C. Kirk Hadaway and Penny Long Marler define the term as follows: "the term 'Mainline Protestant' is used along with 'mainstream Protestant' and 'oldline Protestant' to categorize denominations that are affiliated with the National Council of Churches and have deep historical roots in and long-standing influence on American society."
In the US, Protestantism is generally divided between Mainline denominations and evangelical or theologically conservative denominations. The term is also occasionally used to refer to historic Protestant churches in Canada, Europe, Hong Kong, Latin America, and South Africa. The term has also been applied globally by researchers at Durham University. In some other parts of the world, the term Mainline Protestant is not used. Instead, the term "ecumenical" is used to distinguish similar churches from evangelical denominations. Some have criticized the term Mainline for its alleged White Anglo-Saxon Protestant ethnocentric and elitist assumptions, and its erroneous association with the term "mainstream" since it almost exclusively described White American, non-fundamentalist and non-evangelical Protestant Americans from its origin to the late twentieth century.
Mainline vs. mainstream The term mainstream Christian in academic usage is not equivalent to Mainline Protestant and is often used as an attempt to find impartial sociological vocabulary in distinguishing orthodoxy and heresy. Hence in Christological and doctrinal reference mainstream Christianity is often equivalent to Trinitarianism. Mainline Protestantism should not be confused with Nicene Christianity which is more widely accepted as having the "mainstream Christianity" designation that also includes Catholics, Eastern and Oriental Orthodox believers, and non-Mainline Protestants such as Evangelical, Fundamentalist, Charismatic, Confessional, Confessing Movement, the historically Black church, and Global South Protestants. In the United Kingdom and Australia, the term Mainline Protestant is rarely used, and mainstream does not mean progressive Protestant. Although some supporters and adherents do claim that Mainline Protestant is synonymous with Mainstream Protestant.
Denominations
The largest Mainline churches are sometimes referred to as the "Seven Sisters of American Protestantism," a term apparently coined by William Hutchison. The "Seven Sisters" are: United Methodist Church (UMC) is the largest Mainline Protestant denomination among the "Seven Sisters" with nearly 5.04 million members in the United States in 2024. Evangelical Lutheran Church in America (ELCA) is the second largest Mainline denomination with approximately 2.6 million baptized members and 8,200 congregations at the end of 2025. Episcopal Church (TEC) is third largest, with 1.6 million active baptized members, of whom 1.4 million members are located in the United States in 2022. American Baptist Churches USA (ABCUSA) is fourth in size, with approximately 1.1 million members (2017). Presbyterian Church (USA) (PCUSA) is the fifth largest Mainline denomination, with 1.0 million active members in 8,300 congregations (2025). United Church of Christ (UCC) is the sixth and has about 710,000 members in 2022."A statistical profile 2023", United Church of Christ Christian Church (Disciples of Christ) (DOC) is the seventh and has about 278,000 members as of 2022.
The term 'Mainline' has also been applied to Canadian Protestant churches that share common origins with their US counterparts such as the: United Church of Canada 325,315 members (2023), 1.2 million adherents according to 2021 Canadian Census Anglican Church of Canada 294,931 members (2022), 1.1 million adherents according to 2021 Canadian Census Evangelical Lutheran Church in Canada 111,570 members (2015) Canadian Baptist Ministries 81,685 membersBaptist World Alliance, Members, baptistworld.org, USA, retrieved May 5, 2023 Presbyterian Church in Canada 79,961 members (2019) Christian Church (Disciples of Christ) in Canada 2,606 members
The Association of Religion Data Archives, Pew Research, and other sources also consider these denominations, listed with adherents and members, to be Mainline: Cooperative Baptist Fellowship 700,000 members Religious Society of Friends (Quakers) 350,000 members Mennonite Church USA 100,000 members Church of the Brethren 87,181 members (2021) Reformed Church in America 80,675 members (2025)Church Statistical Data Reformed Church in America International Council of Community Churches 69,276 members (2009) National Association of Congregational Christian Churches 65,392 members (2002) Alliance of Baptists 65,000 members Moravian Church in North America 60,000 members Universal Fellowship of Metropolitan Community Churches 15,666 members (2006) Latvian Evangelical Lutheran Church in America 12,000 members (2007) Estonian Evangelical Lutheran Church Abroad 8,000 members Hungarian Reformed Church in America 6,080 members These same sources also consider "Mainline" other denominations outside the US, including: Anglican Church of Mexico 100,000 members"Panorama de las religiones en México 2010"Consejo Mennonite Church Canada 31,000 members The term is also occasionally used to refer to historic Protestant churches in Europe, Latin America, and South Africa. It has also been applied globally.
Historically Black churches are usually categorized differently from evangelicals or Mainline. However, in 2014 the Christian Century identified that these groups "fit the Mainline description." African Methodist Episcopal Church 2.5 million African Methodist Episcopal Zion Church 1.4 million Christian Methodist Episcopal Church 1.2 million members (2025)
Though not listed as Mainline in either the Association of Religion Data Archives or the Pew Research classifications, two groups also appeal to this label. The practices of the Community of Christ (Latter Day Saint movement), with 250,000 adherentes, are typified as congruent with Mainline Protestantism.. While no longer exclusively Christian, the Unitarian Universalist Association, with 152,958 members and religious education enrollees as of 2024, has been labeled as Mainline or congruent with the Mainline tradition by the UUA, some UU congregations, and data analysts. Roughly 1.7 million Americans identify as Unitarian Universalist (including those in the UUA denomination).
Some denominations with similar names and historical ties to the Seven Sisters Mainline groups are not considered Mainline: The Southern Baptist Convention (SBC) [12.7 million], Lutheran Church–Missouri Synod (LCMS) [1.7 million], the Churches of Christ and Christian churches [1.1 million each],Ron Rhodes, The Complete Guide to Christian Denominations, Harvest House, 2007 the Presbyterian Church in America (PCA) [0.4 million], the Anglican Church in North America (ACNA) [0.13 million], and the Conservative Congregational Christian Conference (CCCC) [0.04 million]. After the recent split of the UMC, the Global Methodist Church (GMC) could be added to this list, though no official census is currently known. Since these groups are too theologically conservative to be considered Mainline, those strictly adhering to historical rules of faith are grouped as confessional, while those without are grouped as evangelical. The Institute on Religion and Democracy considers these denominations to be "Mainline-adjacent" due to their origins in the Mainline Protestant denominations.
Ecumenical relations
Theology
Variation Mainline Protestantism is characterized by theological and ideological pluralism. While doctrinal standards and confessional statements exist, these are not usually interpreted in ways to exclude people from membership. Richard Hutcheson Jr. said that clergy candidates were more likely to be rejected due to "excessive narrowness" than for violating confessional standards.
Mainline churches hold a range of theological orientations—conservative, moderate and liberal. About half of Mainline Protestants describe themselves as liberal. Mainline Christian groups are often more accepting of other beliefs and faiths, affirm the ordination of women, and have become increasingly affirming of gay ordination. A 2021 Pew Research Center survey found that 56% of Mainline Protestants believe that non-Christians, including agnostics and atheists, can go to heaven, compared to around a fifth of evangelical Protestants and 38% of those who attend historically Black churches. Nearly one-third of Mainline Protestants call themselves conservative, and most local Mainline congregations have a strong, active conservative element.Struckmeyer, Kurt. "Mainline Christianity. " Following Jesus Web: 13 Dec 2009 Mainline denominations are historically Trinitarian and proclaim Jesus Christ as Lord and Son of God.