When we think of Judaism, we’re not just thinking of one whole faith that is the same in every way. Just like within Christianity you have Catholics, Protestants, you have Eastern Orthodox within Protestantism, you have evangelicals, Pentecostals, charismatics of these different groups and subgroups, it’s the same with Judaism. In ancient times as well as today. The three main branches of Judaism are Orthodox, Conservative (which does not mean morally conservative but Orthodox conservative) and Reformed. Even to the left of Reformed is reconstructionist, to the right of orthodox, ultra Orthodox and within that Hasidic ultra-orthodox Jews. So you have these different groups, these different spectrums. But in the ancient world, in the days of Jesus, the Apostles, there were three main groups. Look at what Paul says in Acts 23:6-7.
Now when Paul perceived that one part of the Sanhedrin were Sadducees and the other Pharisees, he cried out in the council “Brothers I am a Pharisee, a son of Pharisees. It is with respect to the hope and resurrection of the dead that I’m on trial. When he had said this if the sanction arose between the Pharisees and the Sadducees and the assembly was divided. So he knew the differences. The Sadducees held to the five books of Moses only, they did not believe in the future resurrection of the dead, they were temple based. The Pharisees believed that they had oral traditions that were passed on through the generations they ultimately said going all the way back to Moses and they wanted all Jews to live in a sense of ritual purity and they established synagogues in different areas. They’re the ones that survived. Orthodox Jews today can trace directly back to the Pharisees. And then the Essenes, Qumran, Dead Sea Scrolls, they separated from the other groups and lived in a monastic way.