Daniel Boyarin's study of the New Testament gospels will be a controversial book, not because of what it says but because of who says it. Boyarin is Professor of Talmudic Culture and rhetoric at the University of California at Berkeley.
His book, The Jewish Gospels, argues that the ideas that there is a second divine power in heaven, that Jesus kept kosher and that there is a suffering Messiah are ideas that resonated in some circles of Second Temple Judaism. He says this as a Jewish historical scholar. Moreover, he argues against some more skeptical NT scholars that these ideas reflect what Jesus said and taught and are not later products ot early church's theology.
As such, Jesus presented his teaching to reflect an effort to speak to Judaism from within Judaism. Those who work in New Testament Christology or in Second Temple Jewish studies will not be so surprised by what is said or the texts he notes for these themes. That a world renowned talmudic scholar would say it is surprising.
Boyarin works both with Hebrew Scripture texts and with Second temple texts. So for the second power idea, he goes to texts like the Exagoge of Ezekiel, 1 Enoch and 4 Ezra. He works with Mark 7 in discussing Jesus and the idea he kept kosher, even arguing how Jesus' argument fits a halakic and midrashing appraoch that worked in Judaism. He sees Isaiah 53 in individualistic and Messianic terms as fitting within Judaism, noting how such a reading was common in Judaism until recently.
This is an interesting book. There are spots where he overargues the case. He does not note how the Exagoge is a midrash on Exodus 7:1, so it does not teach the deity of Moses as he claims. He may also overreaches on the text where Jesus is said to keep kosher. Jesus appears to have deemphszied this area enough that later the church would not remain concerned about keeping such practices. (But he must have done enough that the Jerusalem church appears ot have been very law abiding as a community) I am not convinced that Jesus' reply of "I am" is a formal violation of blasphemy that matches the standard in the Mishnah. It seem to be a simply affirmatiive response. Still, despite these questions, the book is often quite right in what it points out and highlights-- and in tis general thesis, muhc of what Jesus taught had a backdrop in current Jewish thinking. So this is a volume worth reading to get oriented to the context of the early church's theology. Judaism and Jesus are its sources.