Here is a post at the Secular Right blog concerning the recent comments by Father Gabriele Amorth concerning exorcisms, the Devil, and the Vatican.
Now if you'd like to dismiss what Father Amorth says as nonsense, that's fine. What's interesting about Andrew Stuttaford's mention of it in the context of the Enlightenment ("How's that whole enlightenment thing going") is that, if you substitute "genes" or "memes" for "the Devil" in Father Amorth's comments, you've got a position that many Enlightenment followers would consider reasonable, and perhaps even scientifically established. The Enlightenment presents itself as hard-headed philosophical skepticism, but it always ends up in philosophical doctrines even harder to believe than the medieval notions it allegedly exploded.
There is a hint of this in Twain's comment where he mentions as an afterthought "On the other hand, very few neuroscientists believe in free will now either. Free will is just a useful fiction." Now I find it much easier to believe in the Devil, and even possessed men vomiting glass shards or pieces of iron, than I do that free will is "just a useful fiction." Free will is an obvious and undeniable reality that I experience directly every day; denying it as a "useful fiction" strikes me as incoherent. (If my belief in free will is merely a useful fiction, then isn't my belief that free will is a useful fiction, itself also a useful fiction? Then free will might actually not be a useful fiction. We haven't gotten anywhere, except possibly to increase our confusion.) The existence of the Devil or possessed men are, at least, straightforward propositions that make sense in their own terms. At least I know what it means to affirm or deny them.
The Enlightenment project was never, as advertised, a breakout from darkness into the sunny light of common sense reality. It merely substituted a lot of hard-to-believe propositions with other, even harder to believe propositions.