Is Church-State Separation a Lie?

From an article of the same title by Steven Waldman on beliefnet:

When U.S. Rep. Katherine Harris said separation of church and state is "a lie," many critics figured this was a characteristic Harris gaffe--another sign she was out of the mainstream. Actually, she was reflecting what has become a common view in religious conservative circles--that the idea of separation of church and state was concocted by 20th-century courts, not the Founding Fathers... Conservative activists point out that the words "separation of church and state" appear nowhere in the Constitution--and they're right about that. The phrase came from a letter Thomas Jefferson wrote to a group of Connecticut Baptists in which he praised the First Amendment's "wall between church and state." When the Supreme Court quoted that letter in a key church-state ruling in 1947, the "wall" became the dominant metaphor. While political activists have lately pushed the more combative rhetoric, serious conservative scholars have long argued that the Founders were mostly attempting to block the creation of official state religions when, in the First Amendment, they wrote that Congress could not make laws "respecting an establishment of religion." Therefore, wrote former Supreme Court Justice William Rehnquist, "there is simply no historical foundation for the proposition that the Framers intended to build the 'wall of separation.'" It's also true that when the First Amendment was approved, lawmakers assumed it would only apply to the federal government, allowing the states wide latitude in mixing church and state. (It was the 14th Amendment, passed after the civil war, that applied freedom of religion to the states)... But there's one important difference between mainstream conservative legal scholars and the Christian political activists. Most conservative scholars argue that the Constitution can accommodate a great deal of state support for religion, as long as the government avoids favoring one faith over another. Many modern Christian activists have argued that the U.S. is "a Christian nation" and that the Founders intended not only religion in general, but Christianity specifically... Christian activists usually make the argument by casting the Founders as orthodox Christians, except when it comes to Jefferson, who was downright hostile to organized Christianity.