Christianity is the predominant religion in the United States, although estimates vary among sources. According to a 2024 Gallup survey, approximately 69% of the U.S. population—about 235 million out of 340 million people—identify as Christian. A plurality of Americans identify as Protestant (45%), followed by Catholics (22%). Smaller Christian groups include members of the Church of Jesus Christ of Latter-day Saints (1.5%), Eastern Orthodox Christians (0.5%), and other Christian denominations (0.4%). The United States currently has the largest Christian population in the world, comprising nearly 235 million Christians. However, while the U.S. leads in absolute numbers, several other nations have a greater proportion of their populations identifying as Christian. The United States has the largest Protestant population globally, numbering more than 150 million adherents of different Protestant denominations, and is also the world's fourth-largest country with the highest number of Catholic followers.
The Public Religion Research Institute's "2020 Census of American Religion", carried out between 2014 and 2020, showed that 70% of Americans identified as Christian during this seven-year interval. In a 2020 survey by the Pew Research Center, 65% of adults in the United States identified themselves as Christians. They were 75% in 2015, 70.6% in 2014, 78% in 2012, 81.6% in 2001, and 85% in 1990. By 2005, around 62% of those polled claim to be members of a church congregation. The 2023–2024 Pew Religious Landscape Survey in the United States found that 40% identitied as Protestant and 19% as Catholic.
All Protestant denominations accounted for 48.5% of the population, making Protestantism the most common form of Christianity in the country and the majority religion in general in the United States, while the Catholic Church by itself, at 22.7% of the population, is the largest individual denomination. The nation's second-largest denomination and the single largest Protestant denomination is the Southern Baptist Convention. Among Eastern Christian denominations, there are several Eastern Orthodox and Oriental Orthodox churches, with just below 1 million adherents in the U.S., or 0.4% of the total population. Christianity is the predominant religion in all U.S. states and territories. Conversion into Christianity has significantly increased among Korean Americans, Chinese Americans, and Japanese Americans in the United States. In 2012, the percentage of Christians in these communities were 71%, 30% and 37% respectively.
Christianity was introduced to the Americas during European settlement beginning in the 16th and 17th centuries. Immigration further increased Christian numbers. Going forward from its foundation, the United States has been called a Protestant nation by a variety of sources. When the categories of "irreligion" and "unaffiliated" are included as religious categories for statistical purposes, Protestantism is technically no longer the religious category of the majority; however, this is primarily the result of an increase in Americans, such as Americans of Protestant descent or background, professing no religious affiliation, rather than being the result of an increase in non-Protestant religious affiliations, and Protestantism remains by far the majority or dominant form of religion in the United States among American Christians and those Americans who declare a religion affiliation. Today, most Christian churches in the United States are either Mainline Protestant, Evangelical Protestant, or Catholic.
Christianity in American Civic and Legal Life
The pilgrims who moved to the Americas in the 16th and 17th centuries were searching for religious freedom because of persecution they faced as non-anglican Christians. Today, the United States remains Christian-dominant, with around 68% of people identifying as Christians. But due to how deeply U.S. history is intertwined with Christianity, Christianity continues to influence everyday life in the United States. For example, major holidays, such as Easter and Christmas, are both related to the life of Jesus. On the U.S. currency, words affiliated with Christianity such as "In God we Trust" can be found. During the Pledge of Allegiance, the phrase "under God" is also mentioned. Additionally, when a government official is sworn into office, many put their hand on the Bible. Oftentimes, Congress opens sessions with a prayer. All of these examples show how connected the U.S. is with Christianity on an institutional level.
To understand why these practices are allowed in a country that clearly declares a constitutional separation of Church and State because of its citizens' experience with how it can unfairly empower leader, it is important to understand the concept of ceremonial deism. According to Michael Castagna, ceremonial deism refers to the religious expressions that were originally purely religious but are now seen as cultural or historical. In other words, when a religious phrase or symbol becomes so embedded in public life that it no longer reads as an active endorsement of religion, courts and legal scholar have classified it under ceremonial deism.0
Other legal scholars have also supported this idea that religious language in public life can be constitutional even if it has religious origins. Michael McConnell, a Stanford law professor and former federal judge, argues in "Coercion: The Lost Element of Establishment" that Christianity-affiliated expressions in daily lives in the United States are constitutional because coercion is a required element for violation of the establishment clause. His perspective reinforces Castagna's claim in the sense that the United States government is not forcing a certain belief on the individuals, thus is not a violation of the United States constitution.
This concept directly shows up in how U.S. courts have handled case involving Christianity in public institutions. Marsh v. Chambers focuses on whether legislative prayer in Nebraska violated the Establishment Clause. The Court ultimately ruled that it did not, stating that prayer in government settings is part of a long-standing tradition that dates back to the founding of the United States. The main point is that something can be religious in origin but still treated as cultural or historical practice rather than an endorsement of religion. This was one of the earliest times the Court directly confronted the unclear separation between Church and State, and ceremonial deism was central to how it justified its decision. Decades later, Town of Greece v. Galloway (2014) served as a modern continuation of that same question, the Supreme Court again ruled that prayers are allowed, emphasizing tradition in public institutions in the United States, reinforcing that this was not a one-off phenomenon but a consistent pattern in how American courts treat Christianity as a cultural tradition rather than a purely religious one.
While the concept of ceremonial deism is often drawn as a legitimate source of reasoning for blurry lines in the separation of Church and State, it is controversial and not universally accepted. Steven Epstein, in Rethinking the Constitutionality of ceremonial deism, one of the most cited critiques of ceremonial deism, argues that these unconstitutional endorsements of religion, often perpetuates Christian privilege, actually marginalizes non-adherents. His argument directly pushes against the rationale of ceremonial deism: just because something is repeated often does not remove its religious meaning. In his paper, he highlighted familiar practices such as "In God we Trust" on the U.S. currency and "under God" in the Pledge of Allegiance, again reminding readers that subtle practices that seem regular are not neutral, and in fact favor belief in God while excluding non-believers.
Additionally, critics often question whether Christian expressions in American civic life have truly changed from religious to ceremonial. They cite historical data of U.S. political leadership: nearly all presidents self-identify as Christians. This shows that even though the United States has a clear separation between Church and State in the constitution, Christianity remains embedded in the country's government identity. Moreover, the Trump administration recently took steps to establish the White House faith office and created a task force to eradicate Anti-Christian bias within the government, and provided federal employees guidance on how to support each other's religious expression such as prayer. Many critics in this field of study have argued that this action crossed from ceremonial or neutral usage of Christian-affiliated terms to public endorsement of Christianity.
Major denominational families
Christian denominations in the United States are usually divided into three large groups: two types of Protestantism (evangelical and mainline) and Catholicism. There are also Christian denominations, making up a smaller percentage, that do not fall within the confines of these groups, such as Eastern and Oriental Orthodoxy and various restorationist groups such as the Latter Day Saint movement, Adventists and Jehovah's Witnesses.
A 2004 survey of the United States identified the percentages of these groups as 26.3% (Evangelical), 17.5% (Catholics), and 16% (Mainline); the other groups made up 2.7%. In a Statistical Abstract of the United States, based on a 2001 study of the self-described religious identification of the adult population, the percentages for these same groups are 28.6% (Evangelical), 24.5% (Catholics), and 13.9% (Mainline). Christian religious groups made up 76.5% of the total population, while the other religious groups account for 3.7%. According the 2020 ARDA Database, there were approximately 60 million Christians independent from denominations.
Protestantism
In typical usage, the term mainline is contrasted with evangelical.
The Association of Religion Data Archives (ARDA) counts 26,344,933 members of mainline churches versus 39,930,869 members of evangelical Protestant churches. There is evidence that there has been a shift in membership from mainline denominations to evangelical churches. Additionally, ARDA's 2010 study indicated Baptists were the largest Protestant group throughout the United States, followed by non-denominational Protestants. By 2014, the Pew Research Center determined non- and inter-denominational Protestants became the second-largest Christian group with Baptists third. ARDA's 2020 religion census also counted the movement as overtaking Baptists, making up more than 13.1% of the religious population and 6.4% of the general population.
As shown in the table below (from 2015), some denominations with similar names and historical ties to Evangelical groups are considered Mainline.
Evangelical Protestantism
Evangelicalism is a Protestant Christian movement. In typical usage, the term mainline is contrasted with evangelical. Most adherents consider the key characteristics of evangelicalism to be: a belief in the need for personal conversion (or being "born again"); some expression of the gospel in effort; a high regard for Biblical authority; and an emphasis on the death and resurrection of Jesus. David Bebbington has termed these four distinctive aspects conversionism, activism, biblicism, and crucicentrism, saying, "Together they form a quadrilateral of priorities that is the basis of Evangelicalism."
Note that the term "Evangelical" does not equal Fundamentalist Christianity, although the latter is sometimes regarded simply as the most theologically conservative subset of the former. The major differences largely hinge upon views of how to regard and approach scripture ("Theology of Scripture"), as well as construing its broader world-view implications. While most conservative Evangelicals believe the label has broadened too much beyond its more limiting traditional distinctives, this trend is nonetheless strong enough to create significant ambiguity in the term. As a result, the dichotomy between "evangelical" vs. "mainline" denominations is increasingly complex (particularly with such innovations as the "Emergent Church" movement).
The contemporary North American usage of the term is influenced by the evangelical/fundamentalist controversy of the early 20th century. Evangelicalism may sometimes be perceived as the middle ground between the theological liberalism of the Mainline (Protestant) denominations and the cultural separatism of Fundamentalist Protestantism. Evangelicalism has therefore been described as "the third of the leading strands in American Protestantism, straddl[ing] the divide between fundamentalists and liberals." While the North American perception is important to understand the usage of the term, it by no means dominates a wider global view, where the fundamentalist debate was not so influential.
Historically, Evangelicals held the view that modernist and liberal parties in the Protestant churches had compromised Christian teachings by accommodating the views and values of the secular world. At the same time, they criticized Fundamentalists for their separatism and rejection of the Social Gospel as it had been developed by Protestant activists during the previous century. They argued that the core Gospel and its message needed to be reasserted to distinguish it from the innovations and traditions of the liberals and fundamentalists.
They sought allies in denominational churches and liturgical traditions, disregarding views of eschatology and other "non-essentials," and joined also with Trinitarian varieties of Pentecostalism. They believed that in doing so, they were simply re-acquainting Protestantism with its own recent tradition. The movement's aim at the outset was to reclaim the Evangelical heritage in their respective churches, not to begin something new; and for this reason, following their separation from Fundamentalists, the same movement has been better known merely as "Evangelicalism." By the end of the 20th century, this was the most influential development in American Protestant Christianity.
The National Association of Evangelicals is a U.S. agency which coordinates cooperative ministry for its member denominations.
A 2015 study estimated that the U.S. has about 450,000 Christians from a Muslim background, most of whom are evangelicals or Pentecostals.
Mainline Protestantism
The mainline Protestant Christian denominations are those Protestant denominations that were brought to the United States by its historic immigrant groups; for this reason, they are sometimes referred to as heritage churches. The largest are the Episcopal (English), Presbyterian (Scottish), Methodist (English and Welsh), and Lutheran (German and Scandinavian) churches.
Mainline Protestantism, including the Episcopalians (76%), the Presbyterians (64%), and the United Church of Christ has the highest number of graduate and post-graduate degrees per capita, of any Christian denomination in the United States, as well as the most high-income earners.
Episcopalians and Presbyterians tend to be considerably wealthier and better educated than most other religious groups among Americans, and are disproportionately represented in the upper reaches of American business, law and politics, especially the Republican Party. Numbers of the most wealthy and affluent American families as the Vanderbilts and Astors, Rockefeller, Du Pont, Roosevelt, Forbes, Whitney, Morgans, and Harrimans are historically Mainline Protestant families.
According to Scientific Elite: Nobel Laureates in the United States by Harriet Zuckerman, a review of American Nobel prizes winners awarded between 1901 and 1972, 72% of American Nobel Prize laureates, have identified from a Protestant background. Overall, 84.2% of all the Nobel Prizes awarded to Americans in Chemistry, 60% in Medicine, and 58.6% in Physics between 1901 and 1972 were won by Protestants.
Some of the first colleges and universities in America, including Harvard, Yale, Princeton, Columbia, Dartmouth, Williams, Bowdoin, Middlebury, and Amherst, all were founded by the Mainline Protestants, as were later Carleton, Duke, Oberlin, Beloit, Pomona, Rollins and Colorado College. Most of these schools, however, identify themselves as independent and non-sectarian institutions, having no juridical ties to formal religion.
Many mainline denominations teach that the Bible is God's word in function, but tend to be open to new ideas and societal changes. They have been increasingly open to the ordination of women.
Mainline churches tend to belong to organizations such as the National Council of Churches and World Council of Churches.
The seven largest U.S. mainline Protestant denominations were called by William Hutchison the "Seven Sisters of American Protestantism" in reference to the major liberal groups during the period between 1900 and 1960.
These include:
United Methodist Church: 4,238,097 members (2023)
Evangelical Lutheran Church in America: 2,793,899 members (2023)
Episcopal Church in the United States of America: 1,394,769 active baptized members (2023)
American Baptist Churches in the USA: 1,145,647 members (2017)
Presbyterian Church (USA): 1,094,733 active members (2023)
United Church of Christ: 712,296 members (2022)
Christian Church (Disciples of Christ): 277,864 (2022)
The Association of Religion Data Archives also considers these denominations to be mainline:
Religious Society of Friends (Quakers): 108,500 members
Reformed Church in America: 84,957 members (2023)
International Council of Community Churches: 68,300 members (2010)
National Association of Congregational Christian Churches: 65,569 members (2000)
North American Baptist Conference: 47,150 members (2006)
Moravian Church in America, Southern Province: 21,513 members (1991)
Moravian Church in America, Northern Province: 20,220 members (2010)
Universal Fellowship of Metropolitan Community Churches: 15,666 members (2006)
Latvian Evangelical Lutheran Church in America: 12,000 members (2007)
Congregational Christian Churches (not part of any national CCC body)
Moravian Church in America, Alaska Province
The Association of Religion Data Archives has difficulties collecting data on traditionally African American denominations. Those churches most likely to be identified as mainline include these Methodist groups:
African Methodist Episcopal Church
Christian Methodist Episcopal Church
The Malankara Mar Thoma Syrian Church, an Oriental Protestant body in the Saint Thomas Christian tradition, also has congregations in the United States. This church is in full communion with the Anglican Communion. Hence, the Association of Religion Data Archives groups the Mar Thoma Church with Anglican churches.
Catholic Church
The Catholic Church arrived in what is now the continental United States during the earliest days of the European colonization of the Americas. It secured and established itself formally as early as 1565, with the establishment of the first Catholic parish of the United States at St. Augustine, Florida. It spread in the 1600s through missionaries including Jesuit missionaries like Eusebio Kino, Jacques Marquette, Isaac Jogues and Andrew White. At the time the country was founded (meaning the Thirteen Colonies in 1776, along the Atlantic seaboard), only a small fraction of the population there were Catholic, mostly in Maryland, a "Catholic Proprietary," established in 1634 by the second Lord Baltimore, Cecilius Calvert, 2nd Baron Baltimore; however, as a result of expansion in former French, Spanish and Mexican (i.e., purchase of Louisiana Territory, of Florida, the acquisition of territory after the Mexican–American War) territories, and immigration over the country's history, the number of adherents has grown dramatically and it is now the largest denomination in the United States today. With over 67 million registered residents professing the faith in 2008, the United States has the fourth largest Catholic population in the world after Brazil, Mexico, and the Philippines, respectively.