Demonic fear comes from Satan, not God. Shall He not much more clothe you, Matt. Do not be fearful about what you shall eat or drink, or how you will be clothed. Why are ye fearful, O ye of little faith, Matt. Have faith in God and get rid of your fear.
Nervous habits stem from the emotion of fear.
For the Christian, nervous habits stem from the lack of faith and trust in God and His Provisions. They stem from trusting in yourself or man rather than God. Wives submit yourselves unto your own husbands, as it is fit in the Lord. Husbands, love your wives, and be not bitter against them. Fathers, provoke not your children to anger, lest they be discouraged.