Article VI: The "Supreme Law" and other provisions, #3

"Oath to support the Constitution; no religious test.
The Senators and Representatives before mentioned, and the members of the several state legislatures, and all executive and judicial officers, both or the United States and of the several states, shall bound by oath or affirmation to support this Constitution; but no religion test shall ever be required as a qualification to any office or public trust under the United States." (1)

My concern is that this feels like a loophole advantage for the candidates who are running for the presidency. My reason is that this applies only to people who are Senators, Representatives and president, but not those of who are candidates, who chose to leave their previous office (position). Here's an example, before George W. Bush became a President, he left the office as a Senator to campaign for presidency. Did he use the religion test to qualify himself and the public trust in a way to win votes? Could this be qualify as a loophole? What are your opinions on this?

Link Source:
(1) http://www.nccs.net/freedom_defined/index.htm?const.html&2