The Washington National Cathedral, in Washington, D.C., is a cathedral of the Episcopal Church.

Religion in the United States is characterized by both a wide diversity in religious beliefs and practices, and by a high adherence level. According to recent surveys, 83 percent of Americans identify with a religious denomination, 40 percent state that they attend services nearly every week or more, and 58 percent say that they pray at least weekly.^[1] A majority of Americans report that religion plays a "very important" role in their lives, a proportion unique among developed nations.^[2] Many faiths have flourished in the United States, including both later imports spanning the country's multicultural immigrant heritage, as well as those founded within the country; these have led the United States to become one of the most religiously diverse countries in the world.^[3]

The majority of Americans (60% to 76%) identify themselves as Christians, mostly within Protestant and Catholic denominations, accounting for 51% and 25% of the population respectively.^[4] Non-Christian religions (including Judaism, Islam, Buddhism, Hinduism etc.), collectively make up about 3.9% to 5.5% of the adult population.^[4][5][6] Another 15% of the adult population identifies as having no religious belief or no religious affiliation.^[4] When asked, about 5.2% said they did not know, or refused to reply.^[4] According to the American Religious Identification Survey, religious belief varies considerably across the country: 59% of Americans living in Western states (the "Unchurched Belt") report a belief in God, yet in the South (the "Bible Belt") the figure is as high as 86%.^[4][7]

However, despite this seemingly high level of religiosity, only 9% of Americans in a 2008 poll said religion was the most important thing in their life, compared with 45% who said family was paramount in their life and 17% who said money and their career was paramount.^[8]

The Basilica of the National Shrine of the Immaculate Conception in Washington, D.C., is the largest Catholic church in the United States.

Text of the First Amendment to the country's Constitution: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances." It guarantees the free exercise of religion. The Supreme Court has interpreted this as preventing the government from having any authority in religion.

From the early colonial days, when English and German settlers came in search of religious freedom, America has been profoundly influenced by religion.^[9] That influence continues in American culture, social life, and politics.^[10]

Several of the original Thirteen Colonies were established by settlers who wished to practice their own religion within a community of like-minded people: the Massachusetts Bay Colony was established by English Puritans (Congregationalists), Pennsylvania by British Quakers, Maryland by English Catholics, and Virginia by English Anglicans.