The law of the LORD is perfect, converting the soul: the testimony of the LORD is sure, making wise the simple.
The law of the Lord is perfect, converting the soul. How is this to be reconciled with Paul's denial that spiritual life is to be had by the law? (Galatians 3:21.) For the law х towrat (H8451)] cannot be explained as meaning the Gospel. The solution is, The law is viewed as in itself "holy, and just, and good" (Romans 7:12); not in contrast to the Gospel of grace, as Paul regards it, but as fulfilled in the Gospel, which realizes its spirit in the converted man. "Christ is the end of the law for righteousness to everyone that believeth" (Romans 10:4). The ideal of the perfect law is realized in the God-man, Christ Jesus; then, through Him, in His believing members (Romans 8:4). For, "converting" х mªshiybat (H7725)], the margin has 'restoring.' This is better, as the law is regarded here in relation to believers, whereas Paul regards it in relation to unbelievers, to whom it has in itself no converting power. The law of God is a reviving cordial to believers; because it is the reflection of the comforting attributes of Yahweh Himself, of whom the believer saith, He restoreth my soul (Psalms 23:3). The expression "thy servant" (Psalms 19:11) implies that the Psalmist was at the time in a state of grace. The same appears from Psalms 19:14, "O Lord my strength, and my Redeemer." The law, which seems grievous and hard to those who have not the Spirit, is in the eyes of the spiritually-minded "perfect" - i:e., the perfect expression of God's will, in contrast to the imperfect rules of morality suggested by human reasonings, and therefore it restores their soul. It is perfect itself, and also makes those perfect who are guided by it. The Hebrew for law means a 'directory'. So Luther says, 'The law does nothing of this sort by itself; but it becomes such through the sun's heat, which breaks forth through faith on the Word.'
The testimony of the Lord is sure. "Testimony" is a term applied to the two tables of the testimony (Exodus 25:16), the Decalogue. They were a testimony to the Israelites, that they had taken them as obligatory upon themselves (Kimchi). They are also God's testimony concerning man's duty. The term points to the covenant relation of God to His people, and to His promises, whereby He is pledged to them. Castalio thus distinguishes the different terms (Psalms 19:7-9): The "law," the preceptive part of Revelation; "the testimony" х `eeduwt (H5715)], the doctrinal; the "statutes" х piquwdiym (H6490)], charges given on particular occasions; the "commandment" х mitswat (H4687)], the general body of the divine law; the "fear" of the Lord, religious reverence; the "judgments" of the Lord х mishpªTiym (H4941)], the civil statutes, rules for deciding questions of property, and penal sanctions. All these have an enlarged application under the Gospel. "Sure" implies the certainty of the doctrine of God, as contrasted with the shifting character of man's reasonings about moral and divine truth.
Making wise the simple. The same characteristic is assigned to "all Scripture" in 2 Timothy 3:15, "able to make wise unto salvation through faith which is in Christ Jesus." The ungodly are altogether simpletons: even believers are in themselves "simple" - i:e., spiritually inexperienced; easily misled-until 'the entrance of God's words giveth lights,' yea, 'understanding to the simple' (Psalms 119:130).