For this very reason, you must make every effort to support your faith with goodness, and goodness with knowledge, and knowledge with self-control. (2 Peter 1:5-6 NRSV)
The danger with acting when we are angry, of course, is that we will act foolishly. There is a story of a farmer who was plowing his corn one day when he spotted a mouse gnawing away at a stalk of corn. He thought of the long hours he had spent clearing, planting, and cultivating this field. Now this mouse was trying to destroy it. Anger raged within him. He grabbed a stick and rushed toward the mouse--beating, slashed, chasing until finally he dealt the mouse a lethal blow. A sense of sweet revenge swept over him. Then, he looked around and realized that he had destroyed nearly half an acre of corn to kill one little mouse that couldn't have eaten more than three stalks in an entire season.
Anger can be a great motivating force in our lives, but we must be under control. For we are a living witness for Jesus Christ.
Loving God, may I, even in my anger, be a witness for you. In Jesus' name, Amen.