[W]e should start by looking at the constitution. The First Amendment of the constitution reads:

"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

A strict interpretation of the First Amendment excludes the Jeffersonian language of separation. In the Amendment above, the only phrases that have anything to do with religion are "establishment" and "free exercise." This language implies an indifference towards religion, not an exclusion of it, and certainly not hostility towards it, which is often the posture of our culture.

The establishment clause was influenced by the abundance of religious views in America at the time of its founding. It was written out of openness to all religious beliefs and customs­--the furthest thing from a rejection of religion. It would have been unjust to establish a single national religion.

The free exercise clause is a bit trickier. Properly understanding it requires a working definition of freedom, which I'm not ready to provide. But I don't think it's ridiculous to assume that freedom to practice includes freedom to bring faith to the public square. Freedom of religion is more than being able to practice behind closed doors.

The point is, neither of these clauses is evidence for separation.