Factional Differences Rooted in Law, Not Theology

As the Tanakh tells it, the Jewish nation comprised a united body-politic from the fall of the kingdom of Israel right through the return. The only division in Judaism was between those who followed God's laws, and those who strayed. From the time of the Seleucids on, the people fragmented into factions and religious renewal movements. Prime amongst these were the Pharisees, Sadducees, and Essenes: maybe.