Nor give place to the devil. Ephesians 4:27 (NKJV)
If you keep your anger within certain acceptable bounds, it is not sin. David’s anger is obvious in Psalms. Jesus visibly vented His anger in the temple. Nowhere are these actions described as sin.
But when anger crosses certain boundaries, it becomes sinful behavior. Knowing those emotional and spiritual land lines is difficult, but here are a few helpful guidelines.
Anger is okay as long as it is not a synonym for a constant, irritable temper. If you frequently stew over matters and are quickly irritated, you are not walking in the Spirit. you need His self-control and a mega-dose of biblical love.
Anger is acceptable as long as it is directed at another’s behavior and not the person. God does not treat you as your sins deserve; likewise, you must be careful not to attack a person’s self-worth. Let your anger be directed at the problem, not the person. Don’t always suppress your feelings. Express your ire, but keep it within legitimate bounds.