I think the book is important for reasons such as this example:
The Koran says clearly that Allah does not have a son.
While the fact God gave his son to save mankind from their unsolvable karmic debt, is the whole point of the Christian religion.
Those two do not intersect, so the book basis matters.
And merely believing in the presence of a universal consciousness doesn't erase your karmic debt. While accepting that the universal consciousness sacrificed for you, is all you need to erase your human nature and get 'good' with the consciousness so that you can join with it upon death.
Otherwise you wind up back here to retry for your soul's perfection on your own, again and again and again.