you only trust it if you believe in it. its a guide that points a way to a better relationship with god. Dont get me wrong the bible is good for those looking for answers but in reality it was written by man and has made god accessible through the bible and the word of god. Man has humanised god to suit them not the other way round.
In God I trust - Bible, everyone else has failed the qualification test
I believe that it is trustworthy, and credible.