Why Did Jesus Drive the Money Changers From the Temple?

“When it was almost time for the Jewish Passover, Jesus went up to Jerusalem. In the temple courts he found people selling cattle, sheep and doves, and others sitting at tables exchanging money. So he made a whip out of cords, and drove all from the temple courts, both sheep and cattle; he scattered the coins of the money changers and overturned their tables.” (John 2:13-15 NIV) What does this mean for us today? Why did Jesus drive them out?