"And when He [Jesus] had looked around at them in anger..." (Mark 3:5).
Jesus certainly was angry; but what did He experience in His anger? Did Jesus experience what I experience when I am angry?
The Fathers of the Church teach us that there are two basic "natural passions" (sinless passions or feelings) that might be called desire and irritation. These two natural passions are corrupted by sin to become lust in all of its many forms and anger in all of its forms. Most of the time when we speak of anger, we are referring to an experience that is laced with, if not completely consumed by, sin.
When the Bible speaks of Jesus being angry, we must keep in mind that Jesus is sinless. Jesus experienced all that is natural for a human being, yet without sin. Jesus experienced both desire and irritation, what the Bible normally calls anger and sometimes wrath. However, the "anger" that Jesus experienced was completely free of sin: it was a passionless anger. By "passionless" I do not mean that Jesus did not feel it emotionally. What I mean is that the feeling was not touched by sin and it did not control, push or knock Him off balance. What Jesus experienced was nothing like anger as we generally experience it.
We might say that Jesus was angry, but He was not upset. Jesus could feel the irritation caused by the encounter with injustice and sin, but He never loses control of himself. He never acts in any but the most loving, kind and patient way possible (and "possible" is a key word here). However, Jesus does act, when the time is right and for the salvation of all. It is noteworthy that in St. John's account of the cleansing of the temple, St. John specifically mentions that after Jesus found the money changers in the temple, He took the time to make a whip of cords before He started driving them out. Although He felt "anger," Jesus was not driven by anger even as he was driving out the moneychangers. Jesus did not experience anger as a sinful passion.
This is the reason why it is necessary for Christians (or anyone who wants to change the world) to pursue purity of heart. If we are going to do the works of Christ, if we are going to change evil systems and structures in the world, if we are going to drive the moneychangers out of the various temples of our lives, first we have to purify the passions of our own heart. Otherwise, we will only be fighting fire with fire, attacking one evil with another, their injustice with mine.
Spiritual life, the personal pursuit of purity of heart, is no selfish endeavour. It is the foundation from which action can bring about real change. It is the prerequisite for clear vision. It is the bringing of the Kingdom of Heaven to earth, starting with what I have the most power to change (myself) and moving out from there.