There are Sixty six books of the bible common to Protestants and Catholics.
|Joshua||Judges||Ruth||1 Samuel||2 Samuel|
|1 Thess||2 Thess||1 Tim||2 Tim|
|1 Peter||2 Peter||1 John||2 John|
The Bible is a unique and unified account of God's dealings with the human race. The sixty six books of the bible were written by about 40 different writers over a span of 1500 years. These writers come from different cultures and many different social economic classes.
Its illogical to think that all these people could have somehow gotten together and conspired (over thousands of years) to write a fake document. All kinds of weird theories have been advanced about the books of the Bible and how they came into being. The simplest explanation is that the books of Bible are what they claim to be; i.e. the Word of God.
God could have written His message in clouds across the skies. He could have thundered His message from the heavens. Instead He chose to use human agents; inspired human minds to transmit His thoughts in books of the Bible.
Although printed by human hands the Bibles author and inspiration is God.
Im surprised that this question isnt asked more often because it goes to the heart of what Christians believe.
The Bible is from God. But how do we know that the fellows that wrote it got it right?
The answer has to do not only with the continuity of the book, but also with the continuity of the people.
The Bible is from God. But how do we know that the fellows that wrote it got it right? The answer has to do not only with the continuity of the book, but also with the continuity of the people.
The books of the Bible are the only faith document that claims to have been literally written by the finger of God. And he gave unto Moses two tables of testimony, tables of stone, written with the finger of God .
The story of the Jewish people is the story of redemption. The ten commandants written in stone become the foundation of this people's relationship with God. The history of the Jew is the history of the Bible. They are rightly called the people of the book.
The first Christians were Jews. Instead of a book written by the finger of God, they had the Word which became flesh (Jesus) .
And they had the twelve apostles who were eye witnesses and hearers of Christ. After Christ returned to Glory they wrote down the things Jesus said and did.
By the end of the first century all the apostles were gone. But there were many who knew the apostles and they wrote down what Jesus and the Apostles said and did.
Early Jewish Christians continued the practice of reading the books of the Bible in synagogue, as they had done for centuries.
Only now (When they could do so without opposition and persecution) they began to add the authoritative writings of the eye witnesses of Jesus; i.e. the apostles.
It is these authoritative writings that have come down to us as the canon of scripture. The Greek word kanon means a measuring rod.
Thus the canon of scripture represents the yardstick by which the churchs belief and practice is to be measure; its norms, the list of writings accepted as authoritative and binding. 
God's story of redemption continues. Jews AND Christians are NOW known as the people of the book.
But even with the witness of Jesus and later the apostles and their witnesses, there would inevitably be heresies and controversies and politics that could confuse and divide the baby church.
So God added one more thing to ensure that His people stayed on track. God did something very subtle, but very powerful. God installed an internal witness on the inside of every believer.
He even prophesied (predicted) he was going to do it.
Here is what He did. Listen!
From the Old Testament Book of Ezekiel 36:26-27 (NIV)
26 I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give youa heart of flesh.
27 And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws.
(This prophecy specifically applied to the time of the re-gathering of Israel in the land. But it also applies to all gentiles who become the children of father Abraham by faith in Galatians 3:14)
It is the unerring internal witness of Gods Holy Spirit that allows a believer to discern truth from error.
Jesus said in John 15:26-27 (NIV)
26 "When the Counselor comes, whom I will send to you from the Father, the Spirit of truth who goes out from the Father, he will testify about me.
God's indwelling Holy Spirit confirms the truth in our hearts. We read the Bible. That which we read is confirmed by the Spirit of God. Thus the books of the Bible are authoritative for the believer. The indwelling Holy Spirit alerts every alert believer to that which is not from God.
So, if one comes with another gospel, even if he were a prophet or an angel of light, if this prophet's gospel is not confirmed by the indwelling Holy Spirit of God, it will not be accepted.
Galatians 1:6-9 (KJV)
"6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel: 7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ. 8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. 9 As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed."
Don't be overly concerned if you don't immediately understand all the Bible. For the Bible is not a novel or text book. It is a Spirit Book. Its Word is alive. What matters is that you remember that books of the Bible are real, and they are authoritative for every human being on the planet.
And if the message of the Bible is real, you have to consider the implications of this reality.
If you've never read the Bible; or have never seriously considered its claims; you should start with one of the New Testament books of the Bible. I suggest the gospel of John.
When I read the Bible for the first time, critically. I read the book of Matthew. When I finished, I wondered aloud if the things I read could be real. It seemed to me than and there that it was too fantastic, too good NOT be real. No human mind could conceive of such a narrative.
And so I decided I believed it. And with that belief, I immediately understood and acted upon the implications of that belief. That was thirty years ago. I've never regretted the decision to believe.
The books of the Bible are very interesting, indeed.
(1) J. Vernon McGee (John Vernon) Thru the Bible with J. Vernon McGee; Thomas Nelson, 1981; Vol 1. (2) Wordsearch8 Bible Software. (3) Frank E. Gaebelein Expositors Bible Commentary (NIV), Vol I 1979.