15 For I do not understand my own actions.
For I do not do what I want, but I do the very thing I hate.
16 Now if I do what I do not want, I agree with the law, that it is good.
17 So now it is no longer I who do it, but sin that dwells within me.
“For we know” is one of the ways Paul introduces a new line of thought. In this case he extends his soliloquy to dramatize what he said in verse 13 about sin’s ability to produce death through “the holy and righteous and good” law. The argument in the previous section focused on how sin uses the commandment to bring about death. Now Paul aims his attention at the malevolent power that prevents “I” from fulfilling the law. It is indwelling sin, sin in “me.”“The law is spiritual”
Paul assumes the recipients of his letter agree with him about this elevated description of the law. Paul’s calling the law “spiritual” is unprecedented—a claim not found even in the Old Testament—and it affirms the law’s divine origin. “Flesh” here means the power that holds captive everyone who remains in bondage to Adam’s sin (see 6:6–7), same as in verse 5 where it is the source of the sinful passions that are aroused by the law. “Flesh” describes the status of a non-Christian.
“Sold under sin”
This phrase, coming at the outset of Paul’s portrait of the “I” in this section, can only mean one thing—the person is in bondage to the slavery of sin. It is this phrase “that clinches the argument for a description of a non-Christian here,” says Moo. Paul declared the freedom of believers from the power of sin in chapter 6, particularly verse 14: “For sin will have no dominion over you, since you are not under law but under grace.” People still “under sin” are unregenerate (see 3:9).
Conflict between wanting and doing
In verse 15, “I” expresses the perplexity of not even knowing why he does what he does. This inability to comprehend his own actions, along with being compelled to do what he hates, extends the image of a slave following his master’s bidding. Then verse 16 reinforces the sense of being driven by an unwanted power. The “I” agrees with the law and wants to do it, but is forced to disobey it. Such is the power of indwelling sin (verse 17).
Rescue from the outside
This unwanted power has ruled over humanity ever since the Garden and it could never be dislodged from people’s souls by will or law keeping. Help had to come from the outside. In fact, another “foreign” power, far mightier than sin, came from heaven. Martin Luther used the term “alien righteousness” to describe justification by faith, because God imparts righteousness as a gift from the outside. This gift that conquers sin is available to all who wish to receive it through the Lord Jesus Christ.