Fear of the unknown is a sign of a lack of faith in the God who has called us to cast all our cares upon Him (1 Pet. 5:7). Christ, in His sermon on Mount Olives, also admonished His followers not to worry about tomorrow; they should not worry about what they would eat or drink (Matt. 6:34). Anxiety is a major weakness on the part of melancholies. They always fear the unknown, making them very sensitive to failure, and they mostly have suicidal tendencies. They also have low self-esteem, they are very rigid, and inflexible. In the text above, the Apostle Paul admonishes Christians to be anxious for nothing.
Although Social psychologists believe that a little anxiety in a person sparks some adrenalin of life to make us move in our endeavours, it becomes detrimental when it causes us to fear. This is obviously what Paul is speaking against and would want us to overcome. Because melancholies are usually perfectionists, it becomes difficult sometimes to please them. However, they are goal-oriented and very loyal. Such individuals are able to remain faithful to God, their families and employers. They usually have self-control as compared to the other temperamental traits.
Moses has been cited by many theologians as a good example of a melancholic, who wouldn’t want to take up any leadership position for the fear of being rejected by the Israelites (Ex. 3:13; 4:1,10). Thus, apart from the above identifiable weaknesses in the melancholies, they can become very loyal and faithful to God, their families or employers.