One complicating factor in understanding the Gospels (and the rest of the New Testament) is that the Bible does not present to us a unified, Jewish-based religion founded on the same faith and teachings as the ancient patriarchs. Instead, we are presented with different flavors of a religion known as Judaism, which, although it had similarities with Old Testament teachings, was mainly composed of self-righteous religious traditions.
In his monumental work called "Antiquities of the Jews," the Jewish historian Flavius Josephus (37 to 100 A.D.) lists at least four main non-Christian religious sects of first century Judaism. They are the Pharisees, the Sadducees, the Essenes and a sect founded by Judas the Galilean (the Zealots). Only two of these are specifically called sects in the New Testament. They are the Pharisees (Acts 15:5) and the Sadducees (Acts 5:17). One partly political-based party, the Zealots, is only reference in Scripture (Acts 5:37).
Specific sects and other related grouping of people not listed by Josephus, but which are discussed in the Bible (and covered in this series), include the disciples of John the Baptist, the elders, the priests, the Sanhedrin, the scribes and the Herodians. Each group claimed a monopoly on the truth (either regarding God or political in nature) and usually argued and fought with one another over the correctness of their respective views.
It may seem, by reading the Gospels that a great number of people belonged or associated with a particular party or group. At no time, however, did any group or sect constitute a majority.