You are speaking like that doesnt happen in your own country where a priest or a religious figure does official ceremonies for your king or queen!
IMO, The US is a secular state where church is not forced upon the citizens of the country!
And remember that America's founding fathers fled Europe from religious suppression and they went there for religious freedom.
Any how, IMO, The US is a secular state (may not be a secular society) but in terms of govt it is a secular one!
good source for books on the issue
http://www.wallbuilders.com/