The Democrats don't have to attack her faith at all.
They can completely knock her out of the ball park by pointing out her obvious lack of professional qualifications for this job. That is reason enough.
In the end they could not argue credibly that Roberts did not have the qualifications for the Supreme Court. They can very credibly argue that Miers does not.
Exactly. And if they do that, then they HAVEN'T disqualified her on the basis of her Christianity. And that sets the precendent that Christian faith does not disqualify one for high government office.
The problem is that Bush promised a justice in the mold of a Thomas, a Scalia, and failed to deliver.
Miers might happen to be a constitutionalist but she is not easily identified as such. And since the Constructionists have been burned before (and Jimmy Carter was allegedly "born-again"), the assurances given to date are insufficient.
Cheers!