It is of vital importance to them that their beliefs be based on the Bible and not on mere human speculations or religious creeds. They feel as did the apostle Paul when he expressed himself under inspiration: "Let God be found true, though every man be found a liar." (Romans 3:4, New World Translation*) When it comes to teachings offered as Biblical truth, the Witnesses strongly endorse the course followed by the Beroeans when they heard the apostle Paul preach: "They received the word with the greatest eagerness of mind, carefully examining the Scriptures daily as to whether these things were so." (Acts 17:11) Jehovah's Witnesses believe that all religious teachings should be subjected to this test of agreement with the inspired Scriptures, whether the teaching is offered by them or by someone else. They invite you—urge you—to do this in your discussions with them.
From this it is apparent that Jehovah's Witnesses believe in the Bible as the Word of God. They consider its 66 books to be inspired and historically accurate. What is commonly called the New Testament they refer to as the Christian Greek Scriptures, and the Old Testament they call the Hebrew Scriptures. They rely on both of these, the Greek and the Hebrew Scriptures, and take them literally except where the expressions or settings obviously indicate that they are figurative or symbolic. They understand that many of the prophecies of the Bible have been fulfilled, others are in the course of fulfillment, and still others await fulfillment.
*Source: Watchtower the Official Web Site of Jehovah's Witnesses