The Greek word used for fear in Acts 9:31 and 1 John 4:18 is the same, but they have different connotations based on the scripture context and is therefore describing a different type of fear in different situations. The word is phobos, which can mean fear, terrors, fright, astonishment, amazement, trembling, concern, a terror, an object or cause of terror, reverential fear, awe, respect, deference.
“For God has not given us a spirit of fear, but of power and of love and of a sound mind.” 2 Timothy 1:7
The Greek word for fear in 2 Timothy 1:7 is delia, which means timidity. It is related to timid, which means lacking in courage or confidence.
The only type of fear God wants us having is the fear of the Lord: Fully Expressing Awesome Reverence to Him. When we have this godly type of fear and know His love for us, then it casts out the terror and trembling and concern and worries which the world will throw upon us. And we definitely won’t be lacking in courage or confidence because our confidence will be in Jesus Christ our Lord and Savior who conquered death, hell, and the grave.
We’ll also have wisdom because Proverbs 9:10 says, “The fear of the LORD is the beginning of wisdom, And the knowledge of the Holy One is understanding.” The key to gaining that wisdom is the fear of the Lord. When we become insensitive to our sin, then we’ve lost the fear of the Lord. We’ve gained wisdom when we acknowledge the dangers of sin and cling to Him.
The world wants us to have the wrong kind of fear: False Evidence Appearing Real. When we look at that word phobos (reverential fear, awe) and we begin to fear man, disease, poverty, rejection, abandonment, losing prestige in certain circles, etc., then we in essence have devoted our reverence, which should be toward God Almighty, to something that does not deserve our reverence. And in doing so, we inadvertently become idolatrous.
So let us have courage, because God gave us a spirit of power, love, and a sound mind, not the spirit of fear (timidity), and direct our reverence to the One who has saved us, sanctified us, and filled us with His Holy Spirit. For His love has cast out the fears of the world. Let us as the body of Christ truly reverence our Heavenly Father in the name of Jesus under the power of the Holy Spirit, and be living epistles of His kingdom.