>What it all comes down to is the same for you as for most everyone else. You believe as you are predisposed to believe. The book does not matter. You believe in the Bible because you choose to believe in the Bible. Others believe in the Koran for exactly the same reasons you use for your belief in the Bible. I knew folks back in the mid sixties who believed in the I Ching for similar reasons.
I did believe in I Ching (or, closer, Yi Jing) but not really what it says - which is murky and symbolic anyway. I found out that the sentences you get, no matter how random, are good triggers for my own mind to unleash some dormant ideas, views etc, while thinking about the question at hand. So, IMO, it does work - by letting your own mind do the work.
>Circular arguments are pointless.
I believe in the book because the book says I should believe in it is to me nothing more than a lazy person's way to abdicate the responsibility we all have to think rationally and critically. It's an argument that could be used to push for a belief in every silly diet and self help book ever written.
Not the only responsibility shaken off. For unbelievers, there's "you'll have to live with it", and there's no "but {insert a deity here} will absolve you". Free will means responsibility. There are no excuses like "but God is on our side, no way we can be wrong".