Constitutional event concerning the religion and the government, the Supreme Court has faced two fundamental challenges. First is to give suitable effect to the first Amendment's dual restriction on laws respecting an establishment of the religion and laws prohibiting the free exercise.
Court sometimes has treated these two provisions as the conflicting, at other times it has sought to identify values that underlie both of them. One suggested common value is separation between the institutions of church and state, or more broadly between religious ideas and government.Second value is government neutrality toward religion in the sense of equal treatment among religions and between religion and nonreligious activities. Finally a different sense of neutrality emphasizes private choice in matters of religion without state interference. In particular cases, these values sometimes coincide but at other times conflict.

National leaders and specialists in the study of diplomacy alike, the notion religion affected United States foreign policy is familiar too familiar. American public values from Protestant Christianity toward religious pluralism and secularism. From the founding era well into the 1900s, Protestant religion was thought to be a crucial component of public values. In the last half century, American public life has become much more secular, because government adoption of any religious ideal appears unacceptably partial in a pluralistic society.
Direct financial support of churches and clergy by government was characteristic of the Anglican establishment, the government grants of financial or other concrete aid to churches have always raised significant constitutional issues. The statistical evidence unimportant, that holding the program's primary effect was permissible because the favor was neutral between religious schools and the other schools. Principal battleground concerning official religious activities has been the public schools.

Alexis de Tocqueville wrote in 1835 the religious aspect of the country was the first thing that struck my attention. Throughout American history visitors have remarked on the religious character of the United States. G. K. Chesterton for instance concluded that America thought of itself in religious terms and that the United States was a nation with the inspiration of a church.