US Constitutional Law/Freedom of Religion

"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof ..." "In the words of Jefferson, the clause against establishment of religion by law was intended to erect "a wall of separation between church and State.""

Can I smoke peyote as part of my religion (even if it violates Federal drug laws)? What about practicing bigamy? Do I have to pledge allegiance to the flag if my religion forbids it? And what about prayer -- can I do it in a school? What about at a town council meeting? In deciding these kinds of cases, the Supreme Court has, over time, developed principals to regulate conflicts between religion and law.

Religious freedom is guaranteed by the U.S. Constitution in the First Amendment as quoted above. It has two components, corresponding to the two clauses in the amendment's text: the separation of church and state, which is proclaimed in the Establishment Clause ("Congress shall make no law respecting an establishment of religion") and the freedom of each individual to exercise their religion, expressed in the Free Exercise clause ("or prohibiting the free exercise thereof"). This dual guarantee protects the individual from a government institutionalization of religion, and at the same time protects individuals from a government hostile to their religion. However, the fifteen word guarantee in the First Amendment wouldn't reach it's full potential until the 20th century.

The freedom of religion is guaranteed by the Constitution in the First Amendment. The text of the constitutional prohibition against religious establishment is called the Establishment Clause; the text of the guarantee of the "free exercise" of religion is the Free Exercise Clause. Initially, these First Amendment freedoms meant that the national government could not abridge the religious rights of individuals. In the early 20th century, these freedoms were "incorporated against the states" through the Fourteenth Amendment [see Incorporation and Cantwell v. Connecticut, 310 U.S. 296 (1940)]

Established religion
"Congress shall make no law respecting an establishment of religion..."

History
By the early 18th century, all 13 American colonies were founded and had a state-supported religion. On December 15, 1791, the First Amendment was ratified along with the other 9 amendments of the Bill of Rights. The First Amendment, forbade congress from passing laws to establish a national religion. However it did not forbid states from establishing a state religion. By 1833, with Massachusetts's passing Amendment IX to its constitution, all the states had disestablished religion.

Free Exercise
"Congress shall make no law ... prohibiting the free exercise [of religion]…"

From a casual reading of the amendment, the free exercise clause implies that individuals are free to follow a religion's customs since laws cannot prohibit it as such. Indeed, if Congress were ever to make a law that explicitly prohibits the religious practice in name is itself unconstitutional. However, the Supreme Court has limited the interpretation where the law is facially neutral.

The interpretation regarding the free exercise clause has historically shifted continuously between the "action-belief" distinction and the "compelling interest" requirement. The Supreme Court often changes its understanding of this clause that the current doctrine may not be reliably stated without stating a possible exception. For the most part, The Supreme Court assumes the doctrine of Action-Belief more than the compelling interest requirement.

Action-Belief Doctrine
The early doctrine, Belief-Action, held that belief and opinion is constitutionally protected but action is not. This early doctrine was likely established in Reynolds v. United States, 98 U.S. 145 (1879). The Supreme Court addressed many questions but of interest to us is this: Should the accused have been acquitted if he married the second time [while still married to the first wife], because he believed it to be his religious duty? The Supreme Court answered the question as such:

"Laws are made for the government of actions, and while they cannot interfere with mere religious belief and opinions, they may with practices... So here, as a law of the organization of society under the exclusive dominion of the United States, it is provided that plural marriages shall not be allowed. Can a man excuse his practices to the contrary because of his religious belief? To permit this would be to make the professed doctrines of religious belief superior to the law of the land, and in effect to permit every citizen to become a law unto himself. Government could exist only in name under such circumstances. [Emphasis added.]

...The only defen[s]e of the accused in this case is his belief that the law ought not to have been enacted. It matters not that his belief was a part of his professed religion: it was still belief, and belief only."

While Reynolds made it clear the Action-Belief doctrine of the Supreme Court, due to the large amount of cases of polygamy due to the religious practice from mostly members of the Church of Jesus Christ of Latter-day Saints (LDS), informally known as Mormons, Congress passed legislation that effectively barred bigamists, polygamists, and any person cohabiting with more than one woman from suffrage or jury duty. This 1882 Congressional legislation was sustained by the Supreme Court in Murphy v. Ramsey, 114 U.S. 15 (1885).

Later, Congress enacted legislation that allowed the expropriation of property and the repeal of the charter of the church for the purposes of disallowing polygyny practices. The Supreme Court also sustained this in The Late Corporation of the Church of Jesus Christ of Latter-Day Saints v. United States, 136 U.S. 1 (1890), stating that since Congress acquired the territory through treaty, created legislation that made it so that the established corporations will be following the laws of the U.S. and Utah formerly, and the LDS was public corporation, Congress had the full right to repeal the charter of the corporation, id. pp. 44-46, and abrogate its property as such, id. p. 47.