I think you may be misunderstanding me. Her original statement was "show me in the Constitution where it says separation of church and state" or something similar. Now, her opponent responded with the statement that the First forbade Congress to make a law respecting an establishment of religion.

But. The phrase "separation of church and state" was in one of the Jeffersonian epistles, with a link to Wikipedia. He felt the first amendment created that separation.
http://en.wikipedia.org/wiki/Separation_of_church_and_state

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.