What does John 1:24 mean?

These interrogators (John 1:19–23) were sent from the Pharisees, an extremely legalistic sect of Judaism. They were one of several distinct sects in ancient Judea, such as the Sadducees, Zealots, and Essenes. The most influential were the Sadducees and the Pharisees. Sadducees were more political, more worldly and high-class, and much less spiritual than their peers. Sadducees rejected the idea of resurrection and took a highly figurative approach to the law of Moses.

Pharisees, however, prided themselves on knowing the Mosaic law, knowing it well, and following it with fanatical detail. Their oral traditions had created hundreds of additional rules beyond those of Moses, to ensure that they would not break one of the laws. They were scholarly and extremely moral. For this, many people gave them admiration. Yet they were also legalistic and very authority-centered, which is why they did not understand John the Baptist's use of baptism.

After the destruction of the temple in AD 70, Pharisee theology survived as Rabbinic/Talmudic Judaism, and is today considered Orthodox Judaism. The Sanhedrin court which tried Jesus prior to His crucifixion was composed of seventy Pharisees and Sadducees.