Why does the Bible say that the fear of God is the beginning of wisdom?
The Apostle Paul spoke about wisdom in 1 Corinthians 3, and he puts it in anything but a flattering manner for humanity. He wrote that “the wisdom of this world is folly with God. For it is written, “He catches the wise in their craftiness” (1 Cor 3:19). Maybe Paul was quoting Job because Job wrote that God “catches the wise in their own craftiness, and the schemes of the wily are brought to a quick end” (Job 5:13), so the wisdom of mankind is just plain foolish to God. Besides, “No wisdom, no understanding, no counsel can avail against the LORD” (Prov 21:30). Paul, almost as if he’s taunting the Ph. D’s of his day, asks, “Where is the one who is wise? Where is the scribe? Where is the debater of this age? Has not God made foolish the wisdom of the world” (1 Cor 1:20)? He asks them, “where are they,” because none can ever be wiser than God, even though many think they’ve got God figured out, or they’ve tried to explain Him away, usually by theoretical hypothesis (i.e. evolution). 
Fear of God
Going back to Solomon, we see again that wisdom is from the Lord, or from above, but more specifically, “The fear of the LORD is the beginning of wisdom, and the knowledge of the Holy One is insight” (Prov 9:10). Have you noticed that the fear of God is mentioned more in the wisdom literature than in any other place in the Bible? That means there is a connection between wisdom and the fear of God. As God often does when He wants us to remember something, He inspires Solomon to repeat the truth that “The fear of the LORD is the beginning of knowledge,” but the flip side of that means, “fools despise wisdom and instruction” (Prov 1:7). Since the Book of Job is also considered part of the wisdom literature, he also reiterates the idea that wisdom is tied to the fear of God. He said, “Behold, the fear of the Lord, that is wisdom, and to turn away from evil is understanding” (Job 28:28). A wise man or woman will turn away from evil because they fear or respect God’s Word, so “One who is wise is cautious and turns away from evil, but a fool is reckless and careless” (Job 28:28). Solomon gives us a fitting conclusion for the Book of Ecclesiastes. He wrote, “The end of the matter; all has been heard. Fear God and keep his commandments, for this is the whole duty of man” (Eccl 12:13).
The Book of Proverbs and the Book of James are both considered as part of the wisdom literature of the Bible, and it’s easy to see why. James tells us that the wisdom we seek cannot be found in textbooks or from teachers. Human wisdom “does not descend from above, but is earthly, sensual, demonic. For where envy and self-seeking exist, confusion and every evil thing are there” (James 3:15-16), “but the wisdom from above is first pure, then peaceable, gentle, open to reason, full of mercy and good fruits, impartial and sincere” (James 3:17), so there are only two kinds of wisdom. One is human wisdom, which leads to destruction. The other is that which comes from above, or from God, and that begins with fearing the Lord. To fear God means to have a deep and abiding respect and reverence for God and His Word. Anytime we hear from a teacher, pastor, or author, no matter who they are, are only human. They may have inspiring messages, but only God’s Spirit illuminates God’s Word. The point is, “Every way of a man is right in his own eyes, but the LORD weighs the heart” (Prov 21:2), and “All the ways of a man are pure in his own eyes, but the LORD weighs the spirit” (Prov 16:2). Since Solomon repeats this point more than twice, it must have been a point he wanted us to remember. This doesn’t mean we avoid godly counsel. In fact, Solomon warned that “The way of a fool is right in his own eyes, but a wise man listens to advice” (Prov 12:15), so at times, one of the best things we can do is to “Listen to advice and accept instruction, that you may gain wisdom in the future” (Prov 19:20). Godly wisdom always comes from above, but sometimes God uses godly men and women to dispense that wisdom, but even their wisdom is not their own. Their wisdom was also received from above, but it must be remembered that their fear of God brought them that wisdom…so even though some godly counselors have good and godly counsel, they must point back to God and give Him the glory for their own wisdom. Not one of us can boast or brag about it. We have nothing except that which we have received from God (1 Cor 4:7). Jesus reminds us, “I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing” (John 15:5), and the last time I checked, “nothing” is not a little something.
The wisest thing you could ever do is to put your trust in Jesus Christ. There is no decision that is more important than the one you make in this life about Christ. Whether you trust in Christ or not will determine your eternal destiny, so it is best to decide today, while it is still called “today” (2 Cor 6:2). None of us can “boast about tomorrow, for you do not know what a day may bring” (Prov 27:1). If you reject Christ and He returns, you will face the wrath of God (Rev 20:12-15), however if you put your trust in Him today, you have nothing to fear at His appearing. And that will give you peace of mind as you pillow your head tonight (John 10:27-29), but if you delay this decision, and you were to die, or Jesus would come back, you would face God’s judgment (Heb 9:27). I pray you will trust Him today, if you have not already done so.
Here is some related reading for you: Where Does Wisdom Come From? A Christian Study 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible: English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.