It seems to me that fear is closely associated with our default understanding of God. Indeed, we might even say that for many people, fear is the instinctive emotional response to thoughts of God. Long-established expressions like “to put the fear of God into someone” illustrate just how intimately the emotion of fear is connected with the idea of God.
And, of course, those wishing to draw on the Bible to support the notion that fear is an appropriate response to God can do so with ease. “The fear of the Lord is the beginning of wisdom”, we are told in Proverbs 9:10. And there’s no shortage of accounts throughout the text of scripture where God or his angels appear to strike fear into people’s hearts.
So, fear is typically quite ingrained in our psyche as a response to God, and many assume that the Bible validates its appropriateness.