I know that I'm fighting a losing battle here but, the constitution does NOT prohibit the establishment of a STATE religion. States are free to do what they want in regards to religion. At least that is what the founders had in mind way back then. Else many of the states at the time would not have signed on to a national governmenet. It prohibits CONGRESS from establishing a national religion. It also specificly says that CONGRESS cannot prohibit the free exercise of religion. It seems pretty straight foward to me, but over the years it has morphed into something that none of the members of the original colonies would recognize.
Absolutely they wouldn't. Part of the debate was whether a National Church would supplant such enteties as Maryland's State Church.