I was looking up "pearls" of wisdom for the 12 Days (which I decided not to post after all) and came across this bit of advice.
Faodaidh fearg sealltainn a steach 'an cridh' an duine ghlic, ach còmhnaichidh i'n cridh' an amadain.
Anger may look in on a wise man's heart, but it abides in the heart of a fool.
This goes well with the lesson Paul preached in Ephesians 4:26 "May you be angry, and not sin: Let not the sun set on your anger" ("Biodh fearg oirbh, agus na peacaichibh: na luidheadh a' ghrian air bhur corruich:" )
We talk of the "negative" emotions - anger, hatred, disapproval, lust, pride, envy - and they are negative, but they are not Bad. What makes them sinful is not the feeling of them but what we do with them. In their proper place, they can be forces for good, for positive result.
As a Catholic born and indoctrinated, I find myself feeling queasy saying such a thing about 'lust'. One of the inherent drawbacks to a celibate priesthood is that they are a bit obsessive about the so-called 'sins of the flesh' - or maybe just obsessed. But lust is not in and of itself bad, it is a necessary emotion from a loving Deity designed to ensure the continuation of a creation in which God takes pride and pleasure.
Excessive Anger seems to me go hand in hand with disapproval, hatred, envy, and pride. I don't know if that's simply my perception or my experience, or it if it is so. Righteous anger can incite one to work for justice. Hatred of a situation or act can lead one to ameliorate said situation or to prevent the act from happening. Disapproval - appropriately applied - has in the past served as a deterrent to bad behaviour (one of the breakdowns in modern society is the loss of this. Children know that if they get into trouble, or if any non-related adult tries to call them to account for their actions, their parents will immediately attack the system or adult. Adults know that if they attempt to call another adult to account for bad behaviour, they could get shot.)
Pride can lead us to be the best we can be - to continuously seek self-improvement, to help others, to behave with propriety and grace - because we want to feel proud of ourselves, not ashamed. Again, the Catholic Church is big on shame as a method of control - not so much on pride.
And envy can inspire a person to improve their situation - that's not a bad thing. It's when envy makes one want to take from the object of envy rather that it becomes a problem. Or when the item of envy is ridiculous - a toy, a jewel, a luxury. Envy can go hand and hand with greed, which ... I don't have such a problem with envy myself, but I try to guard myself against getting stuff just because it's 'neat'. I like neat things. Cool things. Toys. and they can be expensive.
I am blessed in that I don't have a problem with anger in myself and I thank God for that. Anger frightens me. My anger. Others can lose their temper, yell and get it out - as if it were some sort of ... game. They never really 'lost it'. But when I got angry, I ... wanted to hurt the other, I didn't care if I got hurt in return, I was going to do damage. To me, anger is a weapon to be used, not a game to play. At some point, I decided that life was a cosmic joke and it was better to laugh and find a way to deal with ... petty aggravations than to get angry.
I still get angry, sometimes, as I did this summer past. I lost something then, something I'll never get back. I don't think that the person who triggered my anger even realizes that it's missing, but I do, and it hurts. But one must do what one must in order to protect oneself, no matter how much it hurts.