Okay, I was curious so I looked into it.
It seems the book is similar to parts of Rabbi Aryeh Kaplan’s, The Real Messiah. R’ Boteach is pointing out where xtian ideology and slogans have their roots in Judaism.
He seems to be filling in the details of how xtianity took water from the well of Judaism and mutated basic concepts.
Further, it seem R’ Boteach has researched yushke from the perspective of some of the Dead Sea Scrolls and the writings of his brother “James” who basically portrays yushke not as the apocalyptical guy in the xtian view, but as someone who was more Jewish than xtians would like to admit.
This is not new stuff. The Israeli Antiquities or whatever Bureau has artifacts that show yushke was like a Jew who wanted to go for the messiah brass ring from the Jewish perspective and not from the view of how xtianity sees him.
That is what the book seems like. Would I write such a book? No. But I did research some of that stuff a long time ago when I wanted to know more about us versus them. For some Jews, they may benefit in finding there is nothing novel about that religion and it is not what it is cracked up to be.
I know many non-affiliated Jews who get sucked in. I, myself, helped to get a family to not go to Jews for yushke meetings and eventually they sent their kids to day school and yeshiva high school.
R’ Boteach may be writing the book for such a purpose. It shows the xtian their relationship to Judaism, while showing the unaffiliated, unlearned Jew, xtianity is not such a special thing to chas veshalom consider and get sucked into.
R’ Boteach may be more clever and doing more good than harm than we realize.