A Preacher teaching a group where he said that it was okay to be angry. One lady was absolutely amazed. She told him that she had been taught all her life that Christians never get angry. So she had reasoned in her mind: "Christians never get angry. I'm always angry.
Therefore I can never be a Christian!"
That night she was freed from 20 years of anguish and received assurance of her salvation. She was indeed a Christian because she had received Jesus as her Savior.
Anger is amoral; that is, of itself it is neither right nor wrong. It's what we do with it and how we handle it that matters. The Bible actually says, "Be angry—sin not."
Anger itself (not rage, hostility or bitterness) is a God-given emotion. Its purpose is to fight evil and right wrongs. This is how Florence Nightingale used her anger. She was angry at the way wounded soldiers were being treated, or rather, not being treated, so she did something about it. We are meant to use our anger in related ways.
The reality is that everybody gets angry at some time or another. Some people bury and deny theirs while others lash out and hurt others. Neither of these is healthy or Christian.
When expressing anger we need to own it as our own, and remember that the biblical principle is to speak the truth in love. One way to do this is to say something like, "I know my feelings are my responsibility, but I feel angry and need to talk to you about such and such."
Never say to a person, "You make me angry." This is because nobody can make us angry without our permission. All they do is trigger our anger but the anger is always ours.
Unfortunately, when we have a lot of bottled up anger or anger from the past that has never been resolved, our anger button can get triggered real easy and we overreact. As I've said many times, what the other person does to me is their issue, How I feel and react is always my responsibility—but to the degree that I overreact, that is my problem.
For healthy, intimate relationships it is imperative that we learn to identify our feelings—positive and negative—to be honest about them, and learn how to handle them in creative, rather than destructive, ways.