"Anger is the result of love. It is enery for the defense of something you love when it is threatened...If something you love is an "ultimate concern," if it is something that gives you meaning in life, then, when it is threatened, you will get enormously angry.
When something becomes more important than G-d, it becomes a defining factor, an "idol of the heart." When such a thing is threatened, your anger is uncontrollable. Your anger is the way the idol keeps you in its service."
~From "The Glory of the Gospel: Studies in Paul's Letter to the Galatians"