I think most religions have strands of truth interwoven with the superstition and miracles. The bible is certainly no exception. Many of the 'historical' referrences in the bible have been independantly proven to have happened.
Also, as with most religions, there are many ideals laid forward that good men should adhere to.
Like all good books, however, the bible had to have something to make the story an interesting read. Like love interests and the occasional supernatural event.
Even today, when people make a movie based on true events, they take certain 'liberties' afterall. Many of the many authors of the bible surely augmented their stories to make them more....appealing.
The overall message is good. Its what following generations have done with that message, twisting and turning it to meet their needs, that the message became less pure.