It is not a sin to become angry. Jesus became angry from time to time. However, anger can cause us to sin if we do not handle it properly. Managing our anger in the right way can help resolve conflicts and solve problems. Mishandling our anger, however, can make an already volatile situation become even worse.
“In your anger do not sin: Do not let the sun go down while you are still angry, and do not give the devil a foothold.”—Ephesians 4:26-27.