This is a subject I keep encountering: why we have certain emotions. Anger I am learning is there to identify a problem, and give enough energy (adrenaline) to fix the problem. Guilt exists to reveal a spirit issue. Fear exists to keep us cautious. The real problem only begins when our emotions rule our actions.
My husband and I had a good talk the other day (about anger and it's purpose). It came after a big clash between husband and 14 y/o stepson. It was an eruption of an ongoing issue about how said stepson acts like leaving our house is an escape from prison. My husband had had enough of the ungratefulness so he reacted. There was yelling and tears. The clash came only hours after my journal prayer time where I focused on my stepson and husband's relationship. Of course during the big blow up I sarcastically thanked God for his "help" in this area. But I am now humbled and repentant for my lack of faith. It is so clear now how God used this "encounter" as a catalist for change. I talked to my husband about my new found knowledge regaurding emotions. My husband actually said "you're right, I never thought about it that way"...(this is a man who'd rather be hung upside down by his toe nails than converse about relational things)...Since then we all are a bit closer.
God is so faithful. He answers prayer. All things work together for the good of those who love Him.