Mainline Protestant

The mainline Protestants (also referred to as modernist Protestants or oldline Protestants) are a group of Protestant denominations in the United States and Canada largely of the theologically liberal or theologically progressive persuasion that contrast in history and practice with 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, as of 2009 they were a minority among American Protestants, claiming approximately 15 percent of American adults. In 2024, approximately 13% of Americans were white non-Hispanic mainline Protestants according to the Public Religion Research Institute's Census of American Religion.

Notable examples of modern-day denominations in the Mainline tradition include the United Methodists, the Evangelical Lutherans, the Episcopalians, the Presbyterians (PCUSA), and the United Church of Christ.