simply not good
I'll deal with this book from two perspective, the story and the theology
Judging from how much the author uses the word in positive ways, one might be safe to assume that one of his favorite words is “simple”, and in keeping with that, this story is by and large a very simple story. If the author had kept the story on the same small scale he started it with, this simple approach may have worked, but he doesn't, things keep getting on a larger and larger scale as the story goes on, but this simple approach begins to sink into simplistic because of it.
For example, the owner of a TV station, after listening to Joshua speak for a few minutes, decides, seemingly at the drop of a hat, to have a TV crew interview Joshua, pp 112-114, an interview that ends taking up about an hour of TV time, pp 138-140. This stretches belief to the breaking point. Then, towards the end, the controversy surrounding this small-town guy somehow becomes so bad that he's summoned to Vatican City to answer for his controversies, and at this point belief completely snaps and tumbles into something more fantasy-like than anything Tolkien wrote.
Another way the simplistic approach to this story shows itself is in how the other characters respond to Joshua, especially the positive responses. It's understandable that the words and actions of the main protagonist in a novel will to a large degree reflect the views of the author, that's not a problem; but when the other characters constantly keep going on about how deep and profound this protagonist's most silly and shallow statements are, how beautiful all his ideas are,and all other such examples of overblown hyperbole, one gets the impression one isn't reading a story intended to be a fair presentation of ideas, and I can't even call this book something like propaganda, but it comes off as if one is reading what the author might think having a fan club would be like, as he surrounds himself, through his protagonists, with people who will accept everything he says without any real criticism or even serious questioning, and who will constantly shower even his most mundane and trite utterances with unconditional praise.
Judging from how much the author uses these words in negative ways, one might be safe to assume that among his least favorites words are “doctrine” and “theology”, with “authority” and “conservative” not far behind.
As the reader soon learns in the story, Joshua is the personification of the author's idea of how Jesus would be if he returned to earth in the modern day; thus, the teachings of Joshua are meant to represent the teachings of Jesus in the New Testament.
The problem is, the teachings of Joshua have little in common with the teachings of Jesus.
For example, there is this statement, from p 73 and taken from a much longer statement, “Jesus came to teach people that they are God's children and, as God's children, they are free, free to grow as human being, to become beautiful people as God intended”. Now, just right off, I can think of a time when Jesus said to some people that “You are of your father, the devil”, John 8:44; in Ephesians 2, Paul writes about a time when the believers in Ephesus used to be “children of wrath, like the rest of mankind”; I John 3:10 offers a contrast between those who are children of God and children of the devil.
And what does the Bible say about why Jesus came? Luke 19:10 records Jesus' statement, in the context of conversing with the tax collector Zacchaeus, that “The Son of Man has come to seek and save the lost”; Matthew 20:28 and Matthew 10:45 record Jesus saying that He, the Son of Man, has come “to give his life as a ransom for many”, that Jesus came to die as a sacrifice for sins, so that we can be forgiven by grace through faith.
This is only one example of how far off this author's Joshua is from Jesus, but it is a strong one. It shows that this author, through his title character, is preaching a false gospel, and practicing great deception by pretending to preach this false gospel through his reimagining of Jesus.
I have a hard time seeing how this work has become some kind of Christian classic, much less why any Christian studio would make a movie based on this book. There is no real Christian content to this book, merely a thin film of Christian-like ideas covering over some completely foul teachings. This book is fit only to be avoided.