Jesus said, "But I will show you whom you should fear: Fear him who, after the killing of the body, has power to throw you into hell" (Luke 12:5, NIV).
Later his apostle John wrote, "And so we know and rely on the love God has for us. God is love. Whoever lives in love lives in God, and God in him. In this way, love is made complete among us so that we will have confidence on the day of judgment, because in this world we are like him. There is no fear in love. But perfect love drives out fear, because fear has to do with punishment. The one who fears is not made perfect in love" (1 John 4:16-18, NIV).
When we first learn about the holiness of God, the wrath of God, and our sins, we fear God. Such a fear is entirely appropriate. We recognize the gravity of our situation. We can see that we deserve hell.
When we learn about the love and grace of God as it was shown on the cross of Christ, our fear begins to be mixed with an strong appreciation of the Lord. While we deserved death and hell, Christ died and faced the wrath of God in our place. Motivated by a mixture of fear and love, we become followers of Jesus Christ.
As we mature, we grow more secure in our relationship with our God. We fear punishment less and love him more.
However, while our fear of punishment subsides, our fear of the Lord does not vanish. It changes. Now we fear the possibility of bringing shame or embarrassment to our Savior. We love him so much that we want to honor him in every way possible.
In some ways, we are like children. In early years, a child will obey because he fears punishment. In later years, his fear will change. He will not want to embarrass his parents by behaving badly. He loves them too much. As Bible teacher Jim Roberts at the Contact Church has said, "By the time I was old enough to realize that I could resist my father, I couldn't."
As hymn writer John Newton put it, "'Twas grace that taught my heart to fear, and grace my fears relieved. How precious did that grace appear the hour I first believed!"