[Comments on Psalm 143:10]: Teach me that I may do thy will. He now rises to something higher, praying not merely for deliverance from outward troubles, but, what is of still greater importance, for the guidance of God’s Spirit, that he might not decline to the right hand or to the left, but be kept in the path of rectitude. This is a request which should never be forgotten when temptations assail us with great severity, as it is peculiarly difficult to submit to God without resorting to unwarrantable methods of relief. As anxiety, fear, disease, languor, or pain, often tempt persons to particular steps, David’s example should bad us to pray for divine restraint, and that we may not be hurried, through impulses of feeling, into unjustifiable courses. We are to mark carefully his way of expressing himself, for what he asks is not simply to be taught what the will of God is, but to be taught and brought to the observance, and doing of it. The former kind of teaching is of less avail, as upon God’s showing us our duty we by no means necessarily follow it, and it is necessary that he should draw out our affections to himself. God therefore must be master and teacher to us not only in the dead letter, but by the inward motions of his Spirit; indeed there are three ways in which he acts the part of our teacher, instructing us by his word, enlightening our minds by the Spirit, and engraving instruction upon our hearts, so as to bring us observe it with a true and cordial consent. The mere hearing of the word would serve no purpose, nor is it enough that we understand it; there must be besides the willing’ obedience of the heart. Nor does he merely say, Teach me that I may be capable of doing, as the deluded Papists imagine that the grace of God does no more than make us flexible to what is good, but he seeks something to be actually and presently done.
He insists upon the same thing in the next clause, when he says, Let thy good Spirit lead me, etc., for he desires the guidance of the Spirit not merely as he enlightens our minds, but as he effectually influences the consent of our hearts, and as it were leads us by the hand. The passage in its connection warns us of the necessity of being sedulously on our guard against yielding to inordinate passions in any contests we may have with wicked persons, and as we have no sufficient wisdom or power of our own by which to check and restrain these passions, that we should always seek the guidance of God’s Spirit, to keep them in moderation. More generally, the passage teaches us what we are to think of free will; for David here denies the will to have the power of judging rightly, till our hearts be formed to a holy obedience by the Spirit of God. The term leading, which I have already adverted to, proves also that David did not hold that middle species of grace which Papists talk so much about, and which leaves man in a state of suspension or indecision, but asserts something much more effectual, agreeably to what Paul says, (Philippians 2:13) that “it is God who works in us both to will and to do of his good pleasure.”
[Comments on Jeremiah 31:33]: He afterwards says, I will put my Law in their inward parts By these words he confirms what we have said, that the newness, which he before mentioned, was not so as to the substance, but as to the form only: for God does not say here, “I will give you another Law,” but I will write my Law, that is, the same Law, which had formerly been delivered to the Fathers. He then does not promise anything different as to the essence of the doctrine, but he makes the difference to be in the form only. But he states the same thing in two ways, and says, that he would put his law in their inward parts, and that he would write it in their hearts. We indeed know how difficult it is that man should be so formed to obedience that his whole life may be in unison with the Law of God, for all the lusts of the flesh are so many enemies, as Paul says, who fight against God. (Romans 8:7) As then all our affections and lusts thus carry on war with God, it is in a manner a renovation of the world when men suffer themselves to be ruled by God. And we know what Scripture says, that we cannot be the disciples of Christ, except we renounce ourselves and the world, and deny our own selves. (Matthew 6:24; Luke 14:26, 27) This is the reason why the Prophet was not satisfied with one statement, but said, I will put my Law in their inward parts, I will write it in their hearts.
We may further learn from this passage, how foolish the Papists are in their conceit about free-will. They indeed allow that without the help of God’s grace we are not capable of fulfilling the Law, and thus they concede something to the aid of grace and of the Spirit: but still they not only imagine a co-operation as to free-will, but ascribe to it the main work. Now the Prophet here testifies that it is the peculiar work of God to write his Law in our hearts. Since God then declares that this favor is justly his, and claims to himself the glory of it, how great must be the arrogance of men to appropriate this to themselves? To write the Law in the heart imports nothing less than so to form it, that the Law should rule there, and that there should be no feeling of the heart, not conformable and not consenting to its doctrine. It is hence then sufficiently clear, that no one can be turned so as to obey the Law, until he be regenerated by the Spirit of God; nay, that there is no inclination in man to act rightly, except God prepares his heart by his grace; in a word, that the doctrine of the letter is always dead, until God vivifies it by his Spirit.
[Comments on Hebrews 8:10]: The first is, that God calls us to himself without effect as long as he speaks to us in no other way than by the voice of man. He indeed teaches us and commands what is right but he speaks to the deaf; for when we seem to hear anything, our ears are only struck by an empty sound; and the heart, full of depravity and perverseness, rejects every wholesome doctrine. In short, the word of God never penetrates into our hearts, for they are iron and stone until they are softened by him; nay, they have engraven on them a contrary law, for perverse passions rule within, which lead us to rebellion. In vain then does God proclaim his Law by the voice of man, unless he writes it by his Spirit on our hearts, that is, unless he forms and prepares us for obedience. It hence appears of what avail is freewill and the uprightness of nature before God regenerates us. We will indeed and choose freely; but our will is carried away by a sort of insane impulse to resist God. Thus it comes that the Law is ruinous and fatal to us as long as it remains written only on tables of stone, as Paul also teaches us. (2 Corinthians 3:3.) In short, we then only obediently embrace what God commands, when by his Spirit he changes and corrects the natural pravity of our hearts; otherwise he finds nothing in us but corrupt affections and a heart wholly given up to evil. The declaration indeed is clear, that a new covenant is made according to which God engraves his laws on our hearts, for otherwise it would be in vain and of no effect.