I read the book. It was ok to put me to sleep each night after about 10 minutes of reading. I've read the Potter books too. I enjoyed them in a light-hearted way. Probably because I went to boarding school. The "Elders" was written with evil intentions, but I don't think DV Code has any such evil pretentions. It's just a fictional mystery.
I've read the book, and I'm not Christian (I'm Jewish). It's entertaining, but factually incorrect. It accepts a hoax as historical truth, presents conjecture as fact, and paints the Catholic Church, and Christianity in general, in a very unfairly negative light.
I would not recommend reading the book, unless you're looking for a cheap thrill. It certainly delivers that, though. Good airport reading, but I wouldn't take it any more seriously (in fact I'd take it less seriously) than a Frederick Forsyth or Tom Clancy book.