The historical information that is mentioned here is generally granted by folks on both sides of this debate, although it is excused in some fashion by our opponents. Supreme Court justices on both sides of this issue have mentioned in their opinions many of the same historical and traditional activities that are mentioned here, specifically with respect to the first Congress hiring chaplains, Congressional prayer, and the Supreme Court invocation. See Zorach v. Clauson and Engel v. Vitale.
Especially encouraged is the perusal of the latter, Engel v. Vitale. This is because, in spite of the fact that this case declared that teacher-led, non-sectarian prayer in public schools is unconstitutional, it rightly shows forth the lack of any practical arguments in favor of separation of church and state extremism. The opinion of the majority cites little in the way of relevant information to support its case, as Justice Stewart brings out clearly in his dissent.
Strangely enough, the information in the Other Examples page is brought out by Justice Douglas in his consent in Engel v. Vitale. See his first footnote.
Consult the early Congressional record for information concerning Congress declaring a day of thanksgiving. See also Gorton Carruth's Encyclopedia of American Facts and Dates (10th ed., p. 107), where he puts the date of the proclamation at November 26, 1789.
For information regarding the history of Sunday, see Daniel J. Boorstin's The Discoverers, pp. 15, 16. See also Europe: A History by Norman Davies, pp. 208, 209. Further information about Constantine can be gleaned from both of those books, as well as in Durant's Caesar and Christ.
And speaking of Durant, two of his volumes contribute greatly to those who wish to learn more about the evils of church/state unification in historical Europe. See specifically The Age of Reason Begins and The Age of Louis XIV. Jasper Ridley's Henry VIII: The Politics of Tyrrany is an excellent source for learning more about that king's struggle with the Vatican, and the subsequent persecution against Catholics as a result. Lacey Baldwin Smith's The Elizabethan World not only is an excellent synopsis of the history of that era, but also provides us with several pertinent examples of the ill consequences which result when a state establishes a religion.
Books of opinion on this matter are numerous and diverse in their positions.
Whether we examine Kranmick and Moore's That Godless Constitution
or Barton's The Myth of Separation, we can find a good deal of information
relevant to this debate, although no third-party opinion books were used
as sources of material for these pages. Matters of opinion quoted in these
pages almost always come from Supreme Court justices.