John 2:15

So he made a whip out of cords, and drove all from the temple area, both sheep and cattle; he scattered the coins of the money-changers and overturned their tables.

It was necessary for every male Israelite 20 years of age or older to pay the Temple tax which was a half of a Temple shekel. The tax could only be paid in Temple shekels since all foreign money was defiled and unsuitable for giving to God, but the moneychangers charged an exorbitant rate for their services. They charged 1/12 of a shekel for each 1/2 shekel they exchanged and another 1/12 if a larger coin was used.

The selling of sacrificial animals could have been a nice convenience if it had not turned into an exploitive racket. The animals had to pass inspection as being without blemish or defect and any animals brought into the Temple from outside were unlikely to pass, since the inspectors were on the take. A pair of doves could cost up to 19 times as much inside the Temple as a pair bought from a market vendor outside. Since there were sometimes as many as 2,250,000 Jews attending the Passover, the sum of money involved is astronomical. However, this was not the reason Jesus cleansed the Temple at thiat particular time.

There were 2 Temple cleansings: this one at the beginning of the ministry of Jesus and the one recorded in Mark 11:15-17 and in Matt. 21:12f and Luke 19:45f at the end of His ministry.  This is the first public action of Jesus and the other Temple cleansing is the last.  In Mark the traders are called robbers “but here the objection is not to their dishonesty, but to their presence.  Jesus is objecting to the practice, and not merely to the way it is conducted.”  (Morris 195)

Mark 11:15-17  On reaching Jerusalem, Jesus entered the temple area and began driving out those who were buying and selling there. He overturned the tables of the money-changers and the benches of those selling doves, and would not allow anyone to carry merchandise through the temple courts. And as he taught them, he said, “Is it not written: “‘My house will be called a house of prayer for all nations’? But you have made it ‘a den of robbers’.”

Making a whip indicates predetermined action.  Jesus did not drive out the moneychangers in an uncontrollable fit of rage; He determined the action He was going to take and carried out those steps necessary to accomplish His goals.

Matthew Henry observes that “He never used force to drive any into the temple, but only to drive those out that profaned it.”