Reply #24: At the time the establishment clause was ratified,

[Igel]

there were official *state* (not federal) religions. The US government wasn't able to force any establishment of religion down their throats. The state I grew up in, IIRC, was officially *Catholic* until years after the Constitution was ratified--and it wasn't unconstitutional. This should give you a clue as to how the clause was interpreted by the founders. Later the Bill of Rights settled down to the state level, but where I grew up there were blue laws (and there still are where I live now).

Jefferson interpreted the separation clause so strictly that he said there was a "wall" between church and the federal government, and without congressional authority--authority that was unconstitutional for Congress to grant--he could not declare a day of thanksgiving; I wonder what he'd think of declaring Xmas a national holiday. Now the clause is interpreted in such a way that Thanksgiving is perfectly constitutional, but other things that were deemed fully constitutional 200 years ago are now considered to have always been unconstitutional.