Appeals to authority are valid arguments only insofar as the authority is an actual authority, and if the truth matches what the authority says.
-On any given philosophical issue, citing Richard Dawkins as an authority is a fallacy. He may, by coincidence, be correct about the issue, but that is not by merit of his "authority" stance - because he is not an authority on philosophy.
-Citing Sam Harris as an authority on a philosophical issue is a much better idea, as he is trained in philosophy. However, he may be incorrect or dishonest in what he says.
In both these cases, what the person says may be taken as a valid argumentative position - only insofar as the position that authority takes is correct.
For a few years now, this former atheist-turned-deist has been paraded by religious folks and degraded by freethinkers. This New York Times article has generated conversation all over the bloggosphere. I'm here to say it doesn't matter.
Flew's conversion from disbelief to belief in a higher power is interesting only if he demonstrates that the arguments which swayed him are valid and should logically sway rational thinkers. As he has simply churned out age-old arguments made invalid since Occam's Razor was formalized (at least), Flew's conversion holds no significance whatsoever.
There has always been an unfair bias among religious people and atheists on this sort of issue. Anthony Flew was undeniably an atheist, and he is now undoubtedly a theist. When a Christian becomes a "poor example" of Christianity (ie. gets involved in scandalizing male prostitution ordeals), he/she is easily shrugged off as "never even was a Christian."
This is how religious people can avoid criticism. Of course, they're quick to jump back to "of course we all fail - but if [someone other than me] fail on a grand scale, it shows she was never a Christian to begin with." This is the "no true scotsman" fallacy. I bring it up in part because, ironically enough, Anthony Flew is credited with having coined the name for that particular logical fallacy.
The point is this: Just as the actions of a theist in no way discredit the argument that "at least one god exists," the decision of an atheist to become a theist in no way weakens atheist arguments. If the motivations for Flew's decision are valid, we have a different story - similarly, if the motives of the misbehaving theist derive from his religious views, we may call into question any cultural acceptance of the particular religious teaching he was following.
Quit focusing on Flew; continue to discuss the arguments that led to his conversion.