Article VI, Clause 3 of the Constitution says "The Senators and Representatives before mentioned, and the Members of the several State Legislatures, and all executive and judicial Officers, both of the United States and of the several States, shall be bound by Oath or Affirmation, to support this Constitution; but no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.
Recently, President Bush explained some of the reasons as to why he selected Harriet Miers for the Supreme Court. "People are interested to know why I picked Harriet Miers, ... part of Harriet Miers' life is her religion."
There were other reasons that he listed, including the quote "She will not legislate from the bench, but strictly interpret the Constitution."
One might argue that when he says "strictly interpret the Constitution," he means "rule the way I want her to rule," given that the letter of the Constitution says no religious test shall be required, yet he listed her religion as the foremost reason he selected her.
Then again, one might argue that he didn't use religion as a test, but rather commented on her whole person, which happens to include religion, and that while he admired her commitment to religion, he did not use it as a balancing factor in determining whether to nominate her or not.
I don't know, I think a strict constructionist view has her nomination going out the window, which would be a shame, because I think the Court could benefit from someone who doesn't have Ivy League credentials and actually knows how to work as a lawyer and a judge.