Christians can become angry just like anyone else.
I have read that both emotional and physical problems can result from anger that is held inside. Some say that anger should be ventilated by such actions as beating a pillow. Some medical authorities say that incorrect handling of stressful situations can cause any one of at least 50 physical diseases. Third, the habit of striking an inanimate object when angry, coupled with the sin of imagining violence against a person, may eventually result in physical violence against a person. I recall a news item about a man who had cursed a police officer.