On April 28, 1952, in the decision of the Supreme Court of   the United States in Zorach v. Clauson, 343 U.S. 306 (1952), in   which school children were allowed to be excused from public   schools for religious observances and education, Justice William   O. Douglas, in writing for the Court stated:

‘The First Amendment, however, does not say that in every and all respects   there shall be a separation of Church and State. Rather, it   studiously defines the manner, the specific ways, in which there   shall be no concern 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. Churches could not be required to pay even   property taxes. Municipalities would not be permitted to render   police or fire protection to religious groups. Policemen who   helped parishioners into their 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   proclamations 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, our 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.”