The thing getting a lot of press in 2004/2005 is the Dan Brown [ Da Vinci Code ] thing.
Much like the other "conspiracy theories", this one is quite successful at attracting the interest of dilettantes with some vague interest in putting together details and pretending they make up a coherent whole.
The novel proposes that the Church has been hiding variously, over the last couple thousand years, that:
Jesus married Mary Magdalene, and had children whose descendents are now in France
The "Holy Grail" was actually her body, the "chalice" that carried the blood of Jesus as she passed it to their descendants
The Nicean meeting in 325 redefined "Christianity", deciding to declare Jesus divine and otherwise redefining things in favor of a paternalistic view that denies the "Grail's" importance
Various patterns in "discredited" religious patterns indicate a suppression of goddess worship which was evidently part of what early Christianity involved
If you're interested in this sort of thing, Foucalt's Pendulum strikes me as a way more interesting way of getting into "Illuminati"-style conspiracy theories.
Unfortunately, however many "fraudulent French fops" associated with "Priory of Sion" tales may be proven to be fraudulent, this will not sway the Da Vinci Code Believer. When faced with confessions, the typical conspiracy buff will shrug and say "Of course they claim they made it up! They're just protecting the conspiracy!"
In effect, to deny the conspiracy is treated as a proof that the conspiracy is real, the "causality" being that if the conspiracy is true, people will deny it. Unfortunately, conspiracy buffs haven't got enough room in their heads (apparently due to various clutter) to simultaneously have that thought in their mind as well as the thought that if the conspiracy isn't real, people will also deny it, presumably in exasperation at the idiots that can evidently believe pretty much anything.