Douthat tries to explain why the Dan Brown's books so popular:
The polls that show more Americans abandoning organized religion don't suggest a dramatic uptick in atheism: They reveal the growth of do-it-yourself spirituality, with traditional religion's dogmas and moral requirements shorn away. The same trend is at work within organized faiths as well, where both liberal and conservative believers often encounter a God who's too busy validating their particular version of the American Dream to raise a peep about, say, how much money they're making or how many times they've been married.
These are Dan Brown's kind of readers.
(Hat tip: Dreher)