Twice in the first eleven verses of Acts 5, Luke records that fear is the result of swift judgment of sin, with the second verse (v.11) indicating that the fear spread beyond the church into the community. The principle is this: When God’s holiness is upheld through his dealing with sin, believers should fear as a result. This proper disposition is actually commanded in Jude 20 But you, beloved, building yourselves up on your most holy faith, praying in the Holy Spirit, 21 keep yourselves in the love of God, waiting anxiously for the mercy of our Lord Jesus Christ to eternal life. 22 And have mercy on some, who are doubting; 23 save others, snatching them out of the fire; and on some have mercy with fear, hating even the garment polluted by the flesh.
This fear is instead of the self-righteousness that is essentially glad someone is getting what they deserve; and instead of callousness that says: “Oh well, we know everyone is a sinner”; and instead of being disillusioned that it’s even possible that immature and professing Christians could sin in such ways, we are to fear sin because of how God hates sin; we are to fear the destructiveness of sin; we are to fear sin because it took the blood of the spotless Lamb of God to pay for our sins and to rescue us from the eternal death our sins deserved. These are the truths that lead to the growth of a church in a way that honors God.