The Christian life is Christ living His life through us today. We can’t do it ourselves, nor can we do it by the law. There is nothing wrong with the Law—let’s understand that—the problem is with us.

What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet.

But sin, taking occasion by the commandment, wrought in me all manner of concupiscence. For without the law sin was dead [Rom. 7:7–8].

Let me try to bring out the meaning a little more clearly: What shall we say then? Is the Law sin? Away with the thought! On the contrary, I should not have been conscious of sin, except through law; for I had not known illicit desire (coveting). But sin, getting a start through the commandment, produced in me all manner of illicit desire. For apart from the Law sin is dead.
Paul, you recall, began his argument way back in the sixth chapter of Romans with this expression, “What shall we say then? Shall we continue in sin?” Now again he says, “What shall we say then? Is the Law sin?” In the first part of this chapter Paul seems to be saying that law and sin are on a par. If release from sin means release from law, then are they not the same? Paul clarifies this. He says, “Perish the thought!” Paul will now show that the Law is good; it reveals God’s will. The difficulty is not with the Law; the difficulty is with us. The flesh is at fault.
Paul becomes very personal in the remainder of this chapter. Notice that he uses the first person pronouns: I, me and myself; they are used forty–seven times in this section. The experience is the struggle Paul had within himself. He tried to live for God in the power of his new nature. He found it was impossible. The Law revealed to Paul the exceeding sinfulness of sin. The Law was an X–ray of his heart. That is what the Law will do for you if you put it down on your life. The Word of God is called a mirror; it reveals what we are. If you have a spot on your face, the mirror will show it to you, but it can’t remove the spot. However, God has a place to remove it:

There is a fountain filled with blood
Drawn from Immanuel’s veins;
And sinners, plunged beneath that flood,
Lose all their guilty stains.

The Law reveals the exceeding sinfulness of sin. The Law is not at fault, but the old Adamic nature is the culprit. The admonition of prohibition contained in the Law makes clear the weakness of the flesh. It shows we are sinners.
Here in California a test was made some time ago. A mirror was put in a very prominent public place, and the test was to see if men or women looked at themselves more. I felt it was an unnecessary test; I could have told them that women looked at themselves more. But unfortunately, the test proved otherwise. We all like to see ourselves. We all like to look in a mirror—except one: the Word of God. We don’t like to look in that one because it reveals us as sinners, horrible, lost sinners.

McGee, J. V. (1991). Thru the Bible commentary: The Epistles (Romans 1-8) (electronic ed., Vol. 42, pp. 126–128). Nashville: Thomas Nelson.