So it's a book of fiction according to you. So why would I follow a admitted book of fiction?
BTW, hard core believers think that the bible IS a science book.
According to me, the Bible is a book of truths, not written in the form of a science textbook. What the Bible can be most accurately likened to is a book of philosophies followed by accounts of people who followed these philosophies.
A science book does not discuss what one should do if his neighbor sues him, what to do with an extra coat, or how we should treat our fellow man. It is wonderful that science tells us about the world we live in, but it says nothing about how we should live our lives in this world.
There are not as many "hard core" as you seem to be indicating. This tells us only that they have little knowledge about this planet where we live, but may also be an indication they still have a strong belief/knowledge on how to live a good life on this planet.