For I delight in the law of God after the inward man: I delight in the law of God after the inward man - Every Jew, and every unregenerate man, who receives the Old Testament as a revelation from God, must acknowledge the great purity, excellence and utility of its maxims, etc., though he will ever find that without the grace of our Lord Jesus he can never act according to those heavenly maxims; and without the mercy of God, can never be redeemed from the curse entailed upon him for his past transgressions. To say that the inward man means the regenerate part of the soul, is supportable by no argument. Ὁ εσω ανθρωπος, and ὁ εντος ανθρωπος, especially the latter, are expressions frequently in use among the purest Greek ethic writers, to signify the soul or rational part of man, in opposition to the body of flesh. See the quotations in Wetstein from Plato and Plotinus. The Jews have the same form of expression; so in Yalcut Rubeni, fol. 10, 3, it is said: The flesh is the inward garment of the man; but the Spirit is the Inward man, the garment of which is the body; and St. Paul uses the phrase in precisely the same sense in 2 Corinthians 4:16, and Ephesians 3:16. If it be said that it is impossible for an unregenerate man to delight in the law of God, the experience of millions contradicts the assertion. Every true penitent admires the moral law, longs most earnestly for a conformity to it, and feels that he can never be satisfied till he awakes up after this Divine likeness; and he hates himself, because he feels that he has broken it, and that his evil passions are still in a state of hostility to it.
The following observations of a pious and sensible writer on this subject cannot be unacceptable: "The inward man always signifies the mind; which either may, or may not, be the subject of grace. That which is asserted of either the inward or outward man is often performed by one member or power, and not with the whole. If any member of the body perform an action, we are said to do it with the body, although the other members be not employed. In like manner, if any power or faculty of the mind be employed about any action, the soul is said to act. This expression, therefore, I delight in the law of God after the inward man, can mean no more than this, that there are some inward faculties in the soul which delight in the law of God. This expression is particularly adapted to the principles of the Pharisees, of whom St. Paul was one before his conversion. They received the law as the oracles of God, and confessed that it deserved the most serious regard. Their veneration was inspired by a sense of its original, and a full conviction that it was true. To some parts of it they paid the most superstitious regard. They had it written upon their phylacteries, which they carried about with them at all times. It was often read and expounded in their synagogues: and they took delight in studying its precepts. On that account, both the prophets and our Lord agree in saying that they delighted in the law of God, though they regarded not its chief and most essential precepts." See farther observations on this point at the end of the chapter, (Romans 7:22-25 (note)).
So far, then, is it from being true that none but a Regenerate man can delight in the law of God, we find that even a proud, unhumbled Pharisee can do it; and much more a poor sinner, who is humbled under a sense of his sin, and sees, in the light of God, not only the spirituality, but the excellence of the Divine law.