It is hard not to admire the way that the Jews have succeeded in maintaining their culture and identity for many thousands of years. This has been achieved in the face of some pretty big practical difficulties. They have rarely had the support of a state and have often been subject to some pretty severe persecutions.
For instance, when Julian became the last pagan to come to the throne they were going through one of their bad patches. The Christians had not that long ago broken away from the Jewish tradition and the two faiths had the kinds of issues that might be expected from a pair that had just been through a messy divorce. Prior to the rise of Christianity the Jews had fallen foul of several of the emperors as a result of a number of brave but not tremendously successful revolts. Hadrian had banned them from Jerusalem. The ban was still in force and on top of that Constantius had imposed extra taxes on them.