Siddharta by Hermann Hesse
damn, this one gets more and more beautiful everytime I read it.
It's about an indian son of a religious man who goes into the world in search of enlightenment.
It's about being able to find your own path to happiness and peace, not blindly following some mainstream religion.

Some reviewers on amazon.com believed that this book is about the Buddha (whose name was Prince Siddharta), and felt that it wasn't an authentic description of Buddha: yes, the protagonists name is "Siddharta"; yes, he goes through most of the stuff Buddha went through; but it is NOT about Buddha. It's about Siddharta and his companion, who struggle to find what they left home looking for.

READ IT!