The divide between Pharisees and Sadducees was the dominant schism in Judaea during the Second and First centuries BC, and one that had a massive effect over Jewish society.
“Pharisee” is a Greek word meaning “those set apart” that identified Jews opposed to Hellenization, while Sadducees were named after their alleged ancestors, high priests during the reigns of David and Solomon, people who were upholders of the Jewish tradition but also willing to compromise with foreign powers and trends.
A case can be made that this schism has never been fully healed.