Tim LaHaye's Babylon Rising series (currently 4 novels):
The First Book goes by the same name of the series, Babylon Rising. It chronicles the adventures of Michael Murphy and how he tries to find the three pieces of The Brazen Serpent. Eventually, instead he finds the golden head of the statue of Nebuchadnezzar.
2.The Secret On Ararat
The Second Book of the series, entitled The Secret On Ararat, again chronicles the adventures of Murphy and Isis and how they search for Noah's Ark in a desperate attempt to prove the Bible correct.
3.The Europa Conspiracy
The Third Book in the series, called: The Europa Conspiracy, is about the rise of the Seven, Michael Murphy's attempt to find the "Handwriting on the Wall" and his growing relationship with Isis Proserpina McDonald, as well as the complication of Talon's attempts to avenge himself against Murphy.
4.The Edge Of Darkness
The Fourth Book in Babylon Rising, The Edge Of Darkness, is about the locating the Lost Ark and deals with safe-guarded Biblical prophecies to expose a conspiracy with terrifying consequences for our modern world, as Michael Murphy sets off to find the Lost Temple of Dagon, and discovers who "Methusela" (the mysterious rich man who had set Murphy on all his quests) is.
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These are great action/adventure stories in the style of Indiana Jones. Warning though that these are Christian novels...so expect some preaching. Don't worry though, the preaching doesn't take away from the story.