If you don't show anger when someone around you is doing or saying wrong, especially with kids then no one knows any difference. It is bad teaching to say not to show anger because someone could end up in danger. Rage is usually where someone is not in control of themselves and this behaviour is completely inappropriate, in any circumstance. Controlled anger is a good thing but liars will take advantage of such a situation to lift themselves up and accuse you of expressing anger. Most christians teach it is wrong to express anger and normal people frown on this behaviour in public. If you are too loud in public or yelling at the kids it upsets those around you. It is better to get up and handle the situation without many words, even if you are feeding baby at the same time. This is considered best behaviour.