Why did Rome tolerate the Jewish religion?
Rome, though pagan, respected any ancient religion. Judaism appeared to Rome as extremely ancient, so Rome permitted Jewish temple worship and did not oppose it until A.D. 70. Christianity, however, was new and therefore unacceptable, prompting Rome to try to stamp it out.
Les explains that Rome put up with the Jewish religion and allowed temple worship at least until 70 A.D. because Rome had respect for any ancient religion, whether their own or someone else's, and in Rome's eyes Judaism was as ancient as you could get. But when Christianity came on the scene, it was not ancient but something new, and that Rome could not go for. Consequently, the Roman Caesars, including Nero, did everything they could to stamp it out. This mentality helps explain why Rome turned vehemently against Christianity while tolerating Judaism.