Good replies have already been offered (archaeological evidence,
fulfilled prophecy, internal consistency, etc.).

I think another piece of evidence is that the people described in
Scripture are real people.  Our Bible "heroes" make mistakes, sin, and
sometimes lack faith.  No one would write a "holy book" where all the
characters are scoundrels or come off looking like buffoons.

Think, for instance, of the cowardly reaction of the disciples after
the arrest of our Lord.  Wouldn't you think that they would want to
edit that portion out if they weren't writing exactly what happened? 
Yet each of the disciples were martyred for their testimony and no one
recanted and said it was all made up.  I think that's pretty strong
evidence of authenticity.


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Grace and peace,
Kevin Sigafoos
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For from him and through him and to him are all things. To him be
glory forever. Amen. (Rom 11:36)