Last time Paul related that the purpose of Torah is to reveal sin and intentions. It functions as it should, just how God designed it.
Romans 7:14-25 (KJV)
For we know that the law is spiritual: but I am carnal, sold under sin.
For that which I do I allow not: for what I would, that do I not; but what I hate, that do I.
If then I do that which I would not, I consent unto the law that it is good.
Now then it is no more I that do it, but sin that dwelleth in me.
For I know that in me (that is, in my flesh,) dwelleth no good thing: for to will is present with me; but how to perform that which is good I find not.
For the good that I would I do not: but the evil which I would not, that I do.
Now if I do that I would not, it is no more I that do it, but sin that dwelleth in me.
I find then a law, that, when I would do good, evil is present with me.
For I delight in the law of God after the inward man:
But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members.
O wretched man that I am! who shall deliver me from the body of this death?
I thank God through Jesus Christ our Lord. So then with the mind I myself serve the law of God; but with the flesh the law of sin.
Based on Paul's examination of the purpose of Torah, he concluded in verse 14 that Torah is spiritual, but he was carnal, sold under sin. The word carnal, in this case, is not referring to anything sinful, but just the fleshly, natural, physical state that humankind is housed in. It can be inferred that mankind is made up of two parts, the spirit and the flesh. The fleshly part is not necessarily sinful either, but to be "sold under sin" means that Paul was driven by fleshly lusts. This truly is the state of all mankind.
For Paul did what he didn't want to do, and he didn't do what he should have done (verse 15) (Paul is using himself as an example of all mankind). In verse 16, Paul said that even if he does what he shouldn't, he understood that the Torah is good. But even though he could see that the Torah is good, Torah was unable to make him good. In a way, he was not responsible for his actions, but rather it was the sin that dwelt within him that was responsible (verse 17). (Although, Paul was saying that his situation was not due to anything that he had created, he was not saying that he was not guilty before God for the sin he committed.)
In verse 18 Paul further explained that even by applying the human will (desiring to do that which is right) he was unable to do the good. No good thing dwelt within his flesh. This statement is in reference to the old nature, that prior to salvation, enslaves mankind to sin.
Verse 19 is somewhat of a repetition of verse 15, but notice that Paul pointed out again that the human will can choose to do good, yet fails to do so. The sin that enslaves overcomes the will.
Verse 20 is a repeat basically of verse 17.
Paul concluded that he found that there was a "law" within himself that counteracted his good will (verse 21). Evil was present within him. This, too, is the case of all mankind.
Paul delighted in Torah in his inner self (verse 22). But there was that other "law" warring against the law of his mind (desiring to obey Torah) that brought him into captivity to the law of sin that existed within his fleshly body (verse 23).
"Oh, wretched man that I am! Who shall deliver me from this body of death?" Here, Paul cried out in desperation. Who would deliver him from this fleshly body that had enslaved him to sin and death (verse 24)?
Paul thanked God through Yeshua. He is able to deliver not only Paul, but all of mankind (verse 25). So, with his mind Paul served Torah, but with his flesh he served the law of sin.
Christianity has traditionally interpreted this passage in one of two ways. Probably, most frequently, this passage is believed to be the back and forth tug of sin upon the believer, but the context instead seems to imply that Paul was describing the state of mankind, in general, and a Torah follower specifically.
The second interpretation is that this is an example of unregenerate man before belief. This understanding comes much closer to what the context seems to imply. In this case, the passage has nothing to do with the struggle with sin believers face after salvation. However, this model fails in that "the good" one desired would not necessarily be Torah, but whatever concept the person had of "good."
What must be remembered is that Paul's point was to demonstrate that Torah was unable to make mankind good, that it is only through Yeshua that righteousness is possible. Only Yeshua can deliver someone from the "body of death."