The best and probably first of the Da Vinci code type of story is Foucault's Pendulum by Umberto Eco. Also I'd reccomend the Name of the Rose by the same author. If you want a laugh while reading about similar themes I'd try anything by Robert Rankine - the Brentford Trilogy is a good starting place with him. The Brentford Trilogy is actually 8 books!
The novels in this series are as follows:
1. The Antipope (1981) - Pooley and Omally take on the resurrected Pope Alexander VI the last Borgia pope.
2. The Brentford Triangle (1982) - Pooley and Omally thwart an alien invasion of Earth when the natives of Ceres (the fifth planet in the solar system before it exploded and became the asteroid belt) come back to the system and seek a new home.
3. East of Ealing (1984) - Pooley and Omally are forced to deal with a high-tech Satanic takeover of Earth by way of barcoding the entire population, aided by a temporally-relocated version of Sherlock Holmes.
4. The Sprouts of Wrath (1988) - the unlikely decision to site the next Olympic Games in Brentford threatens to disrupt Pooley and Omally's way of life, as the evil Kaleton threatens to turn the stadium into a monster to destroy humanity.
5. The Brentford Chainstore Massacre (1997) - as the millennium comes early for Brentford, Dr. Steven Malone finds a way to clone Jesus from the Turin Shroud, as the man called Fred (who sold his soul for ultimate power) attempts to blackmail Pooley into arranging a ceremony that will give his Master power over all the world.
6. Sex and Drugs and Sausage Rolls (2000) - Omally manages a satanic rock group, the lead singer of whom has the power to heal the sick. This book also sees the return of Soap Distant and Small Dave. In this book, Pooley suffers a brutal, but not long-term tragic death.
7. Knees Up Mother Earth (2004) - there's big trouble in little Brentford. Property developers are planning to destroy Griffin Park, the borough's beloved football ground, intending to dig up the creature buried underneath it - namely, the serpent that tempted Eve in the Garden of Eden; the source of original sin. As well as being the seventh book in The Brentford Trilogy, it is also the second book in The Witches of Chiswick Trilogy.
8. The Brightonomicon (2005) - Hugo Rune and his amnesiac assistant Rizla (Revealed at the end to be Jim Pooley) work to stop Count Otto Black from finding the Chronovision. Unlike the other novels in the series, it is set in Brighton and Omally only makes an appearance in the final chapter.
Rankine is wickedly funny and uses some clever concepts.