Zorach v. Clauson (1952)

"The First Amendment, however, does not say that in every respect there shall be a separation of Church and State. Rather, it studiously defines the manner, the specific ways, in which there shall be no concert or union or dependency one on the other.

"That is the common sense of the matter. Otherwise the state and religion would be aliens to each other - hostile, suspicious, and even unfriendly...

"Municipalities would not be permitted to render police or fire protection to religious groups. Policemen who helped parishioners into places of worship would violate the Constitution. Prayers in our legislative halls; the appeals to the Almighty in the messages of the Chief Executive; the proclamation making Thanksgiving Day a holiday; "so help me God" in our courtroom oaths - these and all other references to the Almighty that run through our laws, or public rituals, our ceremonies, would be flouting the First Amendment. A fastidious atheist or agnostic could even object to the supplication with which the Court opens each session: God save the United States and this Honorable Court.

"We are a religious people and our institutions presuppose a Supreme Being... When the state encourages religious instruction or cooperates with religious authorities by adjusting the schedule of public events to sectarian needs, it follows the best of our traditions.

"For it then respects the religious nature of our people and accommodates the public service to their spiritual needs. To hold that it may not would be to find in the Constitution a requirement that the government show a callous indifference to religious groups. That would be preferring those who believe in no religion over those who do believe...

"We find no constitutional requirement making it necessary for government to be hostile to religion and to throw its weighed against the efforts to widen the scope of religious influence. The government must remain neutral when it comes to competition between sects...

"We cannot read into the Bill of Rights such a philosophy of hostility to religion."

See also the article on the U.S. Supreme Court Center