The United States is religiously diverse and historically Protestant-majority, though Protestant affiliation has fallen below half the population in recent decades, with Catholics forming the largest single denomination at around 20 percent, religiously unaffiliated Americans now roughly 28 to 30 percent, and Jewish, Muslim, Buddhist, Hindu and other communities each in the low single digits, per estimates including Pew Research's Religious Composition of the World, 2010-2020 and its own extensive US-specific surveys.
Many of the original thirteen colonies were founded explicitly for religious purposes, including Puritan New England seeking to build a model Christian commonwealth and Catholic-founded Maryland and Quaker-founded Pennsylvania offering unusual, if limited, religious toleration for their era, and the First Amendment's 1791 establishment and free exercise clauses, prohibiting a national church while protecting individual religious practice, created a novel constitutional model that avoided the state-church arrangements common in contemporary Europe. American religious history has produced numerous homegrown new religious movements, including the Church of Jesus Christ of Latter-day Saints founded by Joseph Smith in 1830, Jehovah's Witnesses, Christian Science, Seventh-day Adventism and Pentecostalism, alongside recurring waves of religious revival known as the Great Awakenings that reshaped American Protestant life across the eighteenth, nineteenth and twentieth centuries.