I always found the off-the-cuff conspiracy theory of Jesus from Umberto Eco's magnificent '
Foucault's Pendulum' to be both hilarious and probably closer to the truth than any of us realize.
From the aforementioned book;
"Now that you mention it, lets see. Matthew, Mark, Luke, and John are a bunch of practical jokers who meet somewhere and decide to have a contest. They invent a character, agree on a few basic facts, and then each ones free to take it and run with it. At the end, theyll see whos done the best job. The four stories are picked up by some friends who act as critics: Matthew is fairly realistic, but insists on that Messiah business too much; Mark isnt bad, just a little sloppy; Luke is elegant, no denying that; and John takes the philosophy a little too far. Actually, though, the books have an appeal, they circulate, and when the four realize whats happening, its too late. Paul has already met Jesus on the road to Damascus, Pliny begins his investigation ordered by the worried emperor, and a legion of apocryphal writers pretends also to know plenty...Toi, apo-cryphe lecteur, mon semblable, mon frere. It all goes to Peters head; he takes himself seriously. John threatens to tell the truth, Peter and Paul have him chained up on the island of Patmos. Soon the poor man is seeing things: Help, there are locusts all over my bed, make those trumpets stop, wheres all this blood coming from? The others say hes drunk, or maybe its arteriosclerosis...Who knows, maybe it really happened that way.