When Jesus described the Temple as a “den of robbers,” he was attacking a healthy economic system that developed around the Temple in the first century. Josephus (Antiq. 14.105-109) reported that in 54 B.C. the Roman general Crassus raided the Temple, taking cash reserves weighing about 2000 talents (about 176,000 pounds or 80,000 kilograms, although the “low end” estimate for the value of a talent is a bit less, a total of 151,200 pounds!) Eleazar the priest attempted to give Crassus a gold bar worth tens of thousands of drachmas, but Crassus raided the sanctuary anyway. Most scholars consider these values exaggerated, but no one denies the Temple was very wealthy at the time. A second line of evidence is found in Cicero commenting on the amount of gold confiscated by the Romans in 62 B.C. From The Romans confiscated 220 Roman pounds (165 British pounds) from Apamea, Laodicea, and Adramyttium. Cicero says so much money was being sent out of the Roman provinces to Judea that the Jews in these regions are “impoverished.” This would not have been nearly all of the money being sent to the Temple, but only the money sent by the regions surrounding these three cities.
The sale of required animals for sacrifice was another major factor in the economy of the Temple, and the very practice attacked by Jesus. While we know very little about the sale of birds and other animals in and around the Temple (Sanders, Judaism: Practice and Belief, 86 refers to Leviticus 22:17-15 and Philo, Spec. Laws 1.166), we do know that most worshipers would not have brought the animal with them as the traveled for fear it might be injured on the trip and be rendered unclean (the animal must have no broken bones.) Most animals would therefore have been supplied locally and inspected for purity at the Temple itself. A worshiper may have bought an animal from an “authorized” seller on the Temple premises itself. If an animal was brought in from the outside, the gatekeepers (Levites) could have inspected the animal for defects and passed or rejected it before it was brought into the Temple courts.
Perhaps I am being cynical, but this amount of wealth moving through the Temple had to be a major contributing factor to maintaining the status quo in Jerusalem. Anyone attacking the Temple was threatening the economy of Jerusalem as well as the central symbol of Judaism. In what ways does Jesus challenge the wealth of the Temple?