Before the Holocaust, only few exegetes did serious work on the Jewish background to the New Testament. I have discussed this in my book, Roots of theological anti-Semitism. A rare example of a ‘modern’ scholar is Johannes Weiß, who is foreboding the Jewish turn in exegesis which is beginning to develop in the 1950’s. Another is in certain ways Gerhard Kittel, who saw that ‘Palestinian’ (an anachronistic term, but a technical one in New Testament historiography) Judaism as the natural environment for Jesus, but his anti-Semitism silenced his voice on these matters.
But what would have happened, had not exegesis got delivered from the spell of anti-Jewish ideology? There is no doubt that one can talk of such a ‘Jewish turn’, its breakthrough coming with E.P. Sanders and Krister Stendahl, and many others engaging in exegesis with a more historical orientation. This turn made self-evident what was only quite rare in the early 20th century: to regard the New Testament and Early Christianity as fundamentally Jewish.