The Bible talks a lot about fearing God. “The fear of the Lord the beginning of wisdom,” Proverbs tells us (Prov. 1:7). It’s “a fountain of life” (Prov. 14:27), and “leads to life” (Prov. 19:23).
Understandably the fear of the Lord is important for us to understand. In a passage I frequently return to, the prophet Isaiah writes, “But the Lord of hosts, him you shall honor as holy. Let him be your fear, and let him be your dread” (Isa. 8:13).
So… what does that mean?
This is how Ray Ortlund explains it in Isaiah: God Saves Sinners:
What does this fear of God look like? Verse 13 says: “The LORD of hosts, him you shall regard as holy.” In other words, “Dare to treat God as God. Don’t respond to life in a way that makes God look helpless and weak and worthless.” Living emotionally as if God were not really our Savior is practical atheism. If God is God, he is all that finally matters. The remnant [that is, the faithful people of God] respects God enough to live that way. (Kindle location 1619)
“If God is God, he is all that finally matters,” Ortlund says. Fearing God means respecting Him enough to live that way. Treat Him in a way that reflects who He is. No more, no less.