When Jesus cleanses the Temple (Matt 21:12-13), he seems to have left himself open to charges of being violent or emotional or even sinful. What are we to make of this? -- Grant
You will find my thoughts on this in the NT Chapter notes for this chapter.
Some additional thoughts:
  1. The whip was to drive out animals.
  2. The attack was on the corrupt practices of the priesthood.
  3. Only a very small part of the commercial section of the temple courts was affected. In other words, his goal wasn't to cleanse the temple, but to send a message to Annas and Caiaphas.
  4. In calling it a den of thieves, he was connecting himself with Jeremiah, who also attacked the temple system (Jer 7), predicting its destruction... Comparing Jesus with Jeremiah, you will find many commonalities, and it becomes clear that Jesus identified with this prophet.