The Bible defines a fool as a person without wisdom. He may be a genius, but his thinking is from human viewpoint. He thinks and acts apart from God's standards and controls. A fool is on a rapid downward slide towards destruction, both in this life and the one to come. In the list of terrible sins which characterize the ungodly are several which are either causes or results of anger.
Anger is associated with grieving the Holy Spirit.
And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption. Let all bitterness and wrath and anger and clamor and slander be put away from you, along with all malice. And be kind to one another, tender-hearted, forgiving each other, just as God in Christ also has forgiven you. Notice the contrast here between conditions of anger and the results of impersonal love. Anger is a violation of the Christian's code of conduct as a member of the Body of Christ.