Christopher, I want to answer your question purely from a technical perspective, as I see it. I would find it hard to think that any other work he might have written, or will write, could even remotely approach the impetus of THE DI VINCI CODE in the mind of the reader. And, in my opinion, herein lies the problem. It makes objectivity improbable or impossible for most people.
You read ANGELS AND DEMONS. Whether you read it before or after, do you remember how you approached The DI VINCI CODE (now be honest, it's not easy on this one)? I'm just kidding around with this, but I hope my point makes sense.
I think one of the most difficult things for people to do is to ask themselves why the book was so successful. Overwhelmingly, we hear, as you pointed out, of the religious ramifications, but might this have been a cleverly designed publicity technique?
Is it realistic to think that someone might disavow his/her faith because of a novel--especially when naysayers have proffered the identical argument in hundreds (sic, thousands) of books and articles since the death of Jesus? Maybe, but I don't think so. If a person's faith was that weak to begin with, I submit that this book didn't send him/her over the edge.
So what made the book work? For me, it is the best paced book I have ever read, and I wasn't at all fond of the redundancy and I thought the ending was a complete zero. Yet, I read the book from the moment I got up in the morning, at lunch, standing in line at the post office--well, you get the picture. My wife was the same, and she's never gotten that involved with a story in the 32 years we've been married.
Every single person I talked with about the book, whether they said they liked it or not, could not put it down. For my purposes, this is the lesson.