What is the ruling on reading books that contain words of disbelief (kufr) or polytheism (shirk), and does the reader become a disbeliever (kafir)?

It is not permissible to read books of disbelief (kufr) and polytheism (shirk) except for a valid, recognized Sharia purpose, such as studying, debating, or drawing lessons. The reader is not judged to be a disbeliever unless he believes or approves of what he reads. Furthermore, a specific Muslim is not judged to be a disbeliever until proof (hujjah) has been established against him.