How can you believe the Bible due to the fact it is so old?

A Cult totally denies Jesus Christ or relegates Him to a lessor place.  The Bible is clear in that Jesus is the image of the invisible God. (Colossians 1:15 (NIV))

Who is the liar? It is whoever denies that Jesus is the Christ. Such a person is the antichrist—denying the Father and the Son.  No one who denies the Son has the Father; whoever acknowledges the Son has the Father also.  1 John 2:22-23 (NIV)

Do you think  any group that denies that Jesus Christ is God or claims He was merely a “good teacher” or “moral leader” is a cult?  Do you think people who deny that Jesus is the Christ are liars?  Do you waver on this a little or do you hold strong that Jesus Christ is God?

Now:

The Word Became Flesh – In the beginning was the Word, and the Word was with God, and the Word was God.  John 1:1 (NIV)

If the “The Word” became flesh and was in the beginning what is this saying?  Is this saying that the Bible is an old book or is it just the beginning?