What is the route cause of anger?
Anger is a normal human emotion, and it is a trait we share with our Creator, God, Who exhibits anger toward sin. Therefore, anger can be righteous or it can be unrighteous. The Bible says we may be angry so long as we do not sin through our anger:
Eph. 4:26 BE ANGRY, AND yet DO NOT SIN; do not let the sun go down on your anger,
Scripture also warns against being too quick to show anger:
Prov. 15:1 A gentle answer turns away wrath,
But a harsh word stirs up anger.
Prov. 15:18 A hot-tempered man stirs up strife,
But the slow to anger calms a dispute.
Prov. 16:32 He who is slow to anger is better than the mighty,
And he who rules his spirit, than he who captures a city.
We also recommend listening to Lesson 5D of our Matthew Bible study, which covers the passage where Jesus talks about our anger being enough to condemn us.