For lecture preparation, I am revisiting a fantastic book by Oskar Skarsaune called In the Shadow of the Temple: Jewish Influences on Early Christianity (IVP, 2002).
Here is some material on the evolution of Jewish identity in Antiquity:
Before Alexander the Great and his program of ‘cultural conquest,’ there hardly existed any ‘ism’ in the old world. People defined themselves and their identities mainly by place of origin and ethnic descent…In the wake of Alexander’s conquests, a new way of defining identity appeared. People who were not Greeks by descent, began to talk like Greeks, dress like Greeks, live like Greeks, in Greek-style cities. This new way of life was called, in Greek, hellenismos-probably the first ‘ism’ on record in history. As a response, Jews began to define themselves in the same way: they had their own way of life, iudiasmos. This is a term used, probably for the first time, by the author of 2 Maccabees: Judas Maccabee and his brothers ‘fought bravely for Judaism’ (2 Macc 2:21)…It is obvious that ‘Judaism’ […here…] does not mean Jewishness in a biological sense […but rather…] describes a life according to the Torah; in other words, a certain lifestyle, just like the contrasting concept [hellenism]. (pp. 39-40)