Seek and Ye shall find

I started thinking about the canon as in the canon of the biblical books when one of my non-Christian friends started asking about what constituted the books of the bible and how do we know they're true? I also started thinking about it as some of my Catholic friends were also around the same time asking me to explain why things like the Da Vinci Code are not the truth. My general reaction to the latter has been to fall off the chair laughing and tell them that I find it so obviously false that I cannot believe people can be this gullible. That naturally did not go down well.

At such moments, I'm inclined to remember the scene in Mel Gibson's the Passion, when Pontius Pilate's wife looks at Pilate when he askes of her, "What is Truth?" and she says to him, if you cannot recognise it, then I cannot tell you what it is. (parapharse). That's a reaction I tend to agree with but of course that sheds my hapless questioners no light.
I do have to say though that I was more impressed by my non-Christian friend than my Catholic friends in this respect. He showed a greater desire, a greater willingness to work to find the truth and I am very sure that it is he who will be rewarded with the truth first. If we have this hunger, Christ Himself will find us, after all, did He not promise, Seek and Ye shall Find.

Nevertheless, in order to avoid further criticism of my intellectual hubris, and to respond more sensitively to the requests of my friends to write this all down, I start here with the notion of canonicity.

The Greek word, kanon, originally meant a straight rod, or bar, used for measuring. The metaphorical meaning building on that literal meaning, indicated a measure, a standard. Occasionaly it also simply meant series, or list. It is in these two sense of the word that the "canon" of the bible is used. Nowadays, in Roman Catholic usage, it is used to denote the list of books belonging to the bible. And these books are sacred and inspired by God as opposed to other holy writings or other writings of the time.

Closing question: how is it these books in the bible are recognised as holy and inspired by God and not others, like the Gospel of James, or Judas?