The law of the LORD is perfect, converting the soul...
In this verse, David transitions from meditating on how God's glory is revealed in what He has created, to meditating on God's glory as revealed in His written word. David began his psalm, "The heavens declare the glory of God and the firmament shows His handiwork" (Psalm 19:1). But here, he begins to muse on the many benefits of God’s law as it was revealed to Israel.
The first observation David makes is that the law of God is perfect. In a world where nothing is perfect, it is a great encouragement that God's word is just that—without blemish or mistake. Every word is inspired—God breathed—and as such it reflects His own perfection. Just as everything that God has made reflects His glory, every word in the Bible reflects the majesty of His character.
Furthermore, David declares that an outcome of God's perfect word is that it converts the soul. The suggestion that God uses words written on a page to do something as transcendent and wonderful as to transform evil hearts is absolutely breathtaking. Although creation can give us hints to the character of God, isn't it amazing that something as plain as words can reveal information about God. If embraced with our minds and observed in our hearts, those words will result in a converted soul and give us eternal life?
Paul declares to us that faith comes by hearing and hearing by the word of God (Romans 10:17). But James warns us that simply hearing these divine words is not enough to bring about a true conversion. Be doers of the word, and not hearers only (James 1:22). In this way, the word of God converts the soul and transforms our lives.