Admit it, you've been angry enough to kill. God gets angry. So do we, for we are made in His image.
Anger is the emotional response to a perception of injustice.
God and men are angered when moral law is violated. The law breaker deserves punishment and the punishment for violating God's law is death. In God, anger operates with perfect moral justice. When His law is violated, His wrath is incited, and He acts to bring the sinner to judgment and punishment. God has instituted government to enforce the punishment of wrong doers.