And why spend your money putting the other guy on TV?
You'd do it, too, if your guy looked like this. But seriously, I think the ad is a web-only thing, done on the cheap.
And I don't think it's biblical knowledge the ad is appealing to, so much as specific knowledge of the Left Behind books and movies, and a general familiarity with the ideas of Hal Lindsey, Jack and Rexella Van Impe, and a slew of other prominent premillennial dispensationalists. Whisper campaigns never deal in facts, only prejudices and vague innuendo.