Burton Mack

What do you think about Burton Mack's book, The Lost Gospels? He is basically saying that the New Testament is all a myth.
Since Mr. Mack is a Southern Baptist, I'm curious as to how he thinks he can prove his studies.
I am a born again Christian, but have a friend who believes this everything Mr. Mack has to say in his book.
Can I please get some thoughts or comments on this book.
Joan