23 but I see in my members another law waging war against the law of my mind
and making me captive to the law of sin that dwells in my members.
In verse 21 Paul spoke of the principle—calling it a “law”—that evil thwarts any attempt to do what is right. The word law there signifies not a body of commandments but a general rule of action. Now in these two verses Paul again uses “law” with that same shade of meaning, but he also uses the word in the traditional sense to stand for the Mosaic law. Indeed, law appears four times in these verses, and the result can be confusing until we discern the word’s meaning in each case.
The law of God. This is obviously the law God gave Moses at Sinai.
Another law. The Greek word for “another” also means “different,” and Paul sets this law in contrast with the Mosaic law. It is not simply another way to express the law of God but stands in opposition to God’s law as “a principle of sin, a power, or a controlling force operating within humanity” (Colin Kruse). It is identical to “the law of sin” that takes “I” captive.
The law of my mind. This law is under attack by the “other” law that stands opposed to the law of God. Thus “the law of my mind” is essentially the same as “the law of God” in that the person mentally agrees with God’s law and wants to obey it. Likewise equivalent are “my mind” and “my inner being.” Is Paul therefore speaking of his own Christian experience? Can only a believer delight in the law of God in his or her inner being?
It’s obvious “I” possesses the mind and sentiments of a pious person, but the person need not be a Christian. Indeed, the Christian, having been set free from slavery to sin (6:18–22), cannot still be held captive to the law of sin. Paul’s description could easily represent a pious Jew or pagan God-fearer who might say that the rule (“law”) of his life is to delight in God’s law and have a zeal for God, much as Paul describes his fellow Israelites (Romans 10:2).
As for the phrase “inner being,” Douglas Moo notes that though Paul uses it twice elsewhere to describe a Christian, the phrase is not a technical designation of a believer. Moo cites usage of the phrase in secular Greek to denote man “according to his Godward, immortal side.” It appears that Paul, as Moo says, characterizes the “best” in the non-Christian world to reveal “the utter helplessness of the person apart from Christ who has nothing but his ‘works’ on which to rely for salvation.”According to Richard Longenecker, Paul is appealing to the pagan who aspires to be close to God:
The law of sin. This law—or rather principle—is the same as the “other” law previously noted. It is the power of sin that works through “my members” (limbs or parts of the body) to wage war against the aspirations of the mind. “I” reflects on the sad reality that sin fights with superior force against any intention or desire to obey God’s law.
With this dramatic portrayal of the ironclad rule that indwelling sin makes a person captive to its control, Paul has set the stage for the plaintive cry for deliverance in verse 24, and for God’s answer in chapter 8.