In the United States, freedom of religion is a constitutionally protected right provided in the religion clauses of the First Amendment. The Bill of Rights supports freedom of religion as a legally-protected right, reading that, "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof...". George Washington stressed freedom of religion as a fundamental American principle even before the First Amendment was ratified. In 1790, in a letter to the Touro Synagogue, Washington expressed the government "gives to bigotry no sanction" and "to persecution no assistance." Freedom of religion is linked to the principle of separation of church and state, a concept advocated by Colonial founders such as Dr. John Clarke, Roger Williams, William Penn, and later Founding Fathers, including James Madison and Thomas Jefferson.

The way freedom of religion is interpreted has changed over time in the United States and continues to be controversial. The issue was a major topic of George Washington's Farewell Address. Several American states had their own official state churches both before and after the First Amendment was passed and various Native American religions have been banned for most of US history. Illegal Native American religion was a major cause of the 1890–1891 Ghost Dance War. Starting in 1918, nearly all of the pacifist Hutterites emigrated to Canada when Joseph and Michael Hofer died following torture for conscientious objection to the draft. Some have since returned, but most Hutterites remain in Canada.

The long-term trend has been towards increasing secularization of the government. The remaining state churches were disestablished in 1820 and teacher-led public school prayer was abolished in 1962, but the military chaplaincy remains to the present day. Although most Supreme Court rulings have been accommodationist towards religion, in recent years there have been attempts to replace the freedom of religion with the more limited freedom of worship. Although the freedom of religion includes some form of recognition to the individual conscience of each citizen with the possibility of conscientious objection to law or policy, the freedom of worship does not.

Controversies surrounding the freedom of religion in the US have included building places of worship, compulsory speech, prohibited counseling, compulsory consumerism, workplace, marriage and the family, the choosing of religious leaders, circumcision of male infants, dress, education, oaths, praying for sick people, medical care, worshiping during quarantines, use of government lands sacred to Native Americans, the protection of graves, the bodily use of sacred substances, mass incarceration of innocent Japanese American clergy during World War II, both animal slaughter for meat and the use of living animals, and accommodations for employees, prisoners, and military personnel.

Legal and public foundation The United States Constitution addresses the issue of religion in two places: in the First Amendment, and the Article VI prohibition on religious tests as a condition for holding public office. The First Amendment prohibits the Congress from making a law "respecting an establishment of religion, or prohibiting the free exercise thereof". This provision was later expanded to state and local governments, through the incorporation of the First Amendment.

Colonial precedents The October 10, 1645, charter of Flushing, Queens, New York, allowed "liberty of conscience, according to the custom and practice of Holland without molestation or disturbance from any magistrate or ecclesiastical minister." However, New Amsterdam Director-General Peter Stuyvesant issued an edict prohibiting the harboring of Quakers. On December 27, 1657, the inhabitants of Flushing approved a protest known as The Flushing Remonstrance. This contained religious arguments even mentioning freedom for "Jews, Turks, and Egyptians," but ended with a forceful declaration that any infringement of the town charter would not be tolerated.

When England gained control of New Netherland in 1664, they chose to make no changes to the government principles in what is now New York, but established English Law. The coastal peninsula between the Hudson (North) and Delaware (South) Rivers was mostly unsettled and when colonists applied for permission to settle what is now New Jersey, Governor Nicolls issued a patent that guaranteed religious freedom in New Jersey. The language read, “…any and all persons, who shall plant and inhabit in any of the land aforesaid that they shall have free liberty of conscience, without any molestation or disturbance whatsoever in their way of worship.” Based on this patent, New Jersey is the only colony that had a non-denominational foundation and has guaranteed uninterrupted religious freedom until the present. By 1665 New Jersey had settlements that contained Anglicans, Baptists and Quakers (Friends) and at present has extreme religious diversity.

Freedom of religion was first applied as a principle in the founding of the colony of Maryland, also founded by the Catholic Lord Baltimore, in 1634.Zimmerman, Mark, Symbol of Enduring Freedom, p. 19, Columbia Magazine, March 2010 Fifteen years later (1649), an enactment of religious liberty, the Maryland Toleration Act, drafted by Lord Baltimore, provided: "No person or persons ... shall from henceforth be any waies troubled, molested or discountenanced for or in respect of his or her religion nor in the free exercise thereof." The Maryland Toleration Act was repealed with the assistance of Protestant assemblymen, and a new law barring Catholics from openly practicing their religion was passed.Brugger, Robert J. (1988). Maryland: A Middle Temperament, p 21, Baltimore, Maryland: Johns Hopkins University Press. . In 1657, Lord Baltimore regained control after making a deal with the colony's Protestants, and in 1658 the Act was again passed by the colonial assembly. This time, it would last more than thirty years, until 1692,Finkelman, Paul, Maryland Toleration Act, The Encyclopedia of American Civil Liberties, New York: CRC Press. . when after Maryland's Protestant Revolution of 1689, freedom of religion was again rescinded.Roark, Elisabeth Louise, p.78, Artists of colonial America Retrieved February 22, 2010 In addition in 1704, an Act was passed "to prevent the growth of Popery in this Province", preventing Catholics from holding political office. Full religious toleration was not restored in Maryland until the American Revolution, when Charles Carroll of Carrollton, a delegate of the Colony of Maryland to the Second Continental Congress in Philadelphia, signed the United States Declaration of Independence.

Rhode Island (1636), Connecticut (1636), and Pennsylvania (1682), founded by Baptist Roger Williams, Congregationalist Thomas Hooker, and Quaker William Penn, respectively, established the religious freedom in their colonies in direct opposition to the theocratic government which Separatist Congregationalists (Pilgrim Fathers) and Puritans had enforced in Plymouth Colony (1620) and Massachusetts Bay Colony (1628)."Massachusetts Bay Colony". Encyclopædia Britannica. Having fled religious persecution themselves in England, the leaders of Plymouth and Massachusetts Bay Colony restricted franchise to members of their church only, rigorously enforced their own interpretation of theological law and banished freethinkers such as Roger Williams, who was actually chased out of Salem., as well as banning Quakers and Anabaptists.Allen Weinstein and David Rubel (2002), The Story of America: Freedom and Crisis from Settlement to Superpower, DK Publishing, Inc., New York, N.Y., , pp. 58–63Christopher Fennell (1998), Plymouth Colony Legal Structure <http://www.histarch.uiuc.edu/plymouth/ccflaw.html >Hanover Historical Texts Project <http://history.hanover.edu/texts/masslib.html>M. Schmidt, Pilgerväter, in Die Religion in Geschichte und Gegenwart, 3. Auflage, Band V (1961), Tübingen (Germany), col. 384M. Schmidt, Hooker, Thomas, in Die Religion in Geschichte und Gegenwart, 3. Auflage, Band III (1958), col. 449 These colonies became safe havens for persecuted religious minorities. Catholics and Jews also had full citizenship and free exercise of their faiths.Clifton E. Olmstead (1960), History of Religion in the United States, Prentice-Hall, Englewood Cliffs,74–75, 99–105, 113–115Edwin S. Gaustad (1999), Liberty of Conscience: Roger Williams in America, Judson Press, Valley ForgeHans Fantel (1974), William Penn: Apostel of Dissent, William Morrow & Co., New York, N.Y., Williams, Hooker, Penn, and their friends were firmly convinced that democracy and freedom of conscience were the will of God. Williams gave the most profound theological reason: As faith is the free gift of the Holy Spirit, it cannot be forced upon a person. Therefore, strict separation of church and state has to be kept.Heinrich Bornkamm, Toleranz. In der Geschichte des Christentums, in Die Religion in Geschichte und Gegenwart, 3. Auflage, Band VI (1962), col. 943 Pennsylvania was the only colony that retained unlimited religious freedom until the foundation of the United States. The inseparable connection of democracy, freedom of religion, and the other forms of freedom became the political and legal basis of the new nation. In particular, Baptists and Presbyterians demanded vigorously and successfully the disestablishment of the Anglican and Congregational state churches that had existed in most colonies since the seventeenth century.Robert Middlekauff (2005), The Glorious Cause: The American Revolution, 1763-1789, Revised and Expanded Edition, Oxford University Press, , p. 635

The First Amendment

In the United States, the religious and civil liberties are guaranteed by the First Amendment to the United States Constitution:

The "Establishment Clause", stating that "Congress shall make no law respecting an establishment of religion," is generally read to prohibit the Federal government from establishing a national church ("religion") or excessively involving itself in religion, particularly to the benefit of one religion over another. Following the ratification of the Fourteenth Amendment to the United States Constitution and through the doctrine of incorporation, this restriction is held to be applicable to state governments as well.

The "Free Exercise Clause" states that Congress cannot "prohibit the free exercise" of religious practices. The Supreme Court of the United States has consistently held, however, that the right to free exercise of religion is not absolute. For example, in the 19th century, some of the members of the Church of Jesus Christ of Latter-day Saints (LDS Church) traditionally practiced polygamy, yet in Reynolds v. United States (1879), the Supreme Court upheld the criminal conviction of one of these members under a federal law banning polygamy. The Court reasoned that to do otherwise would set precedent for a full range of religious beliefs including those as extreme as human sacrifice. The Court stated that "Laws are made for the government of actions, and while they cannot interfere with mere religious belief and opinions, they may with practices." For example, if one were part of a religion that believed in vampirism, the First Amendment would protect one's belief in vampirism, but not the practice.

The Fourteenth Amendment