nyc;3320101 said:
This is incorrect. Everything he writes is based on fact, but admits that the book itself is pure fiction. He didn't spend five years researching the Freemasons (The Lost Symbol) looking for non-facts.
Based on fact, doesn't mean everything presented as fact in the book actually is, but the premise behind it is based on some fact. Fiction writers (and sometimes non-fiction writers) take liberties in their writing to make a store more fluid and add interest.
The Lost Symbol talks about Freemasons and I can tell you many things he talked about were certainly true, though not everything. Some of it was obviously fiction and created to add depth to the store or based on rumors of such.
According to your above reasoning, Star Trek is also based on fact because there actually is a planet Earth populated by human beings, and Hellraiser is based on fact because puzzle boxes exist.
Many science fiction and fantasy writers also perform extensive research in order to ensure that their stories are feasible; however, this doesn't mean their books are "based on facts."
Brown's books are factual only in the sense that the Catholic Church and Freemasons are real organizations that operate in a certain way; however, the premises upon which his books are based and the narrative situations in which he places the Catholic Church and the Freemasons are, by his own admission, fabricated -- as in, non-factual.
Brown isn't just taking "liberties." He's creating an entire narrative.