Boteach seems to be writing that yushke was a Jew and lived as such and was not the person he is made out to be in xtianity, and that xtians should have a better understanding of this.
That is what I see is at the core of the book.
Is he correct? I dont know. Are we reacting to him as a response to the view of the xitan yushke? You bet, and rightfully so. I could care less about who he really was or really was not. But others in the world may find some merit to his book.