The idea of fearing God is a basic and fundamental concept in the Old Testament theology. However, the idea is often misunderstood or associated with mixed thoughts and emotions. There are two main reasons for this. First, the concept of fear has different meanings depending on the object. Second, as time goes by, languages develop and the translation of fear gets different associations, influenced by that process and the surrounding culture. In the light of these perspectives, this essay seeks a thorough analysis of the basic hebrew understanding of the idea of fearing God in the Old Testament. To get an answer, or deeper understanding, of what the idea of fearing God means according to the Old Testament theology, an exegetical analysis is performed based on literary criticism and a comparative analysis based on four theological traditions in the Old Testament. The traditions that are examined are deuteronomistic, priestly, poetic and prophetic with focus on Isaiah. Since the understanding of the idea of fearing God affects the understanding of God, God’s will, God’s acts and the human vocation, the subject is important. To not understand who God really is, or what intentions he has, and to be confused by the different significations of the meaning of fear when relating to other persons or things except from God, risks leading to insecurity, confusion, struggle and a lack of trust in God. If God’s intentions seems to be unpredictable, evil and powerful in a bad way, the message of God is being disturbed and misunderstood. To come closer the biblical texts can help us understand the idea of fearing God better and consequently get a more true picture and understanding of God, God’s will, God’s intentions and the human vocation.