He claims it's based on facts.
The book opens with the following statement BEFORE the fiction starts:
FACT:
The Priory of Siona European secret society founded in 1099is a real organization. In 1975 Paris's Bibliothèque Nationale discovered parchments known as Les Dossiers Secrets, identifying numerous members of the Priory of Sion, including Sir Isaac Newton, Botticelli, Victor Hugo, and Leonardo da Vinci.
The Vatican prelature known as Opus Dei is a deeply devout Catholic sect that has been the topic of recent controversy due to reports of brainwashing, coercion, and a dangerous practice known as "corporal mortification." Opus Dei has just completed construction of a $47 million World Headquarters at 243 Lexington Avenue in New York City.
All descriptions of artwork, architecture, documents, and secret rituals in this novel are accurate.
The first paragraph is pure lie. The second paragraph is slander. The third is laughable. It is an attempt at popularization of the Gnostic heresy which specifically denies the divinity of Christ. This is the same theme that Heinrich Himmler embraced as part of the core beliefs of his harmless little group of like minded individuals.
It ain't harmless and it ain't "just fiction." I also don't think it's coincidental that it's coming out and being pushed right now. I bet you Ahmadinejad will heap praise on this movie.