I just watched this movie on video this weekend. Always meant to see it and just got around to it. It was a brilliant movie, but not at all what I was expecting.
It's a story of a man who lives in a world where everyone says what is on their mind all the time, to the point of brutal honesty (No, I am not sleeping with you.")
It is a comedy, but it has a very compelling side story. You see, the first big "lie" was when Ricky Gervais character was at his dying mothers bedside. She is very scared, and too comfort her, he tells her that her death is not the end, and that she will live on in love and in comfort. (don't want to give too much away here...) Doctors overhear this, and because it is assumed that no one can lie, it is automatically believed.
In other words, The Invention of Lying is a movie where the invented lie is the precepts of organized, Christian religion.
It is hilarious from there, in the vein of Monty Python, very British humor, I might add, and very compelling.
This isn't meant to comment on it per se, but the movie does make some potentially uncomfortable points about the willingness of members of organized religion to believe almost anything, even beliefs that are in effect, diametrically opposed to each other.