"By the time of the adoption of the Constitution, our history shows that there was a widespread awareness among many Americans of the dangers of a union of Church and State. These people knew, some of them from bitter personal experience, that one of the greatest dangers to the freedom of the individual to worship in his own way lay in the Government's placing its official stamp of approval upon one particular kind of prayer or one particular form of religious services. They knew the anguish, hardship and bitter strife that could come when zealous religious groups struggled with one another to obtain the Government's stamp of approval from each King, Queen, or Protector that came to temporary power. The Constitution was intended to avert a part of this danger by leaving the government of this country in the hands of the people, rather than in the hands of any monarch. But this safeguard was not enough. Our Founders were no more willing to let the content of their prayers and their privilege of praying whenever they pleased be influenced by the ballot box than they were to let these vital matters of personal conscience depend upon the succession of monarchs. The First Amendment was added to the Constitution to stand as a guarantee that neither the power nor the prestige of the Federal Government would be used to control, support or influence the kinds of prayer the American people can say -- that the people's religions must not be subjected to the pressures of government for change each time a new political administration is elected to office. Under that Amendment's prohibition against governmental establishment of religion, as reinforced by the provisions of the Fourteenth Amendment, government in this country, be it state or federal, is without power to prescribe by law any particular form of prayer which is to be used as an official prayer in carrying on any program of governmentally sponsored religious activity."
January 1, 1970
https://en.wikiquote.org/wiki/First_Amendment_to_the_United_States_Constitution