As we visited in our previous two installments, Douglas Moo describes three different ways in which the man Paul describes in Romans 7 can be identified:
1. Paul describes his experience as an unconverted Jew under the law, a view we saw explained in the previous installment.
2. Paul describes his experience, perhaps shortly after his conversion, as he sought sanctification through the law.
3. Paul describes his experience as a mature Christian.
Sinclair Ferguson advocates for the third view, a post-regenerate Paul (or generic regenerate man) in Romans 7, and sees the apostle as using this pericope to join chapter 6 with chapter 8 and to describe the struggle that the believer has between his remaining corrupt flesh and his new nature:
[T]hese statements simply underline Paul’s sense of the inherent contradiction of being one in whom sin continues to dwell when he or she is not under the dominion of the flesh but in the Spirit. For the one who has realized that the synchronous indwelling of the Spirit of Christ and of sin presents an appalling contradiction – not merely a paradox – is bound to express it in terms that verge on, and perhaps are, contradictory.
Stephen Westerholm also makes an argument for the third position, and in doing so gives us a warning about the danger of using the law as an agent of sanctification:
To seek to define whether he has in mind the Christian or the pre-Christian struggle with sin is probably to ask a question he did not intend to answer; indeed, his account seems to mix elements from both. Most of what he says clearly reflects his Christian perception of life lived under the law, but modern scholarship has perhaps too quickly banished every suggestion of Christian experience from the passage. 7:24–25, if reflective of any experience, would seem to reflect his continuing awareness of the struggle between a mind devoted to God’s service and a “flesh” drawn toward sin.
Moo explains the second, mediating view in his analysis of all three:
The main argument for the second, “immature Christian,” view is, of course, that the arguments for the first and third views both carry weight, and so the only way to reconcile all the data is with a mediating view. Paul is a Christian (explaining the data in the third-view argument), but a Christian who finds himself frustrated because he is trying to live by the law (explaining the data in the first-view argument). But the problem with this mediating view, and the reason I finally think that the passage describes an unregenerate person, is that the data in the argument for the first view involve an objective state, not a subjective feeling. Paul does not say that he feels as if he were a slave of sin or that he feels as if he were a prisoner of the law of sin; rather, he states such as the reality of his situation.
Does it matter to us as an application of Romans 7 which of the three men Paul is describing? Perhaps if we consider the passage only to be applicable to the unregenerate, or more specifically an unregenerate Jew, it might. But I think close inspection will tell us that we — you and I, believer — have a lot in common with the man in Romans 7, and the danger Paul points to in looking back at the law for our sanctification.
Next: Completed by the Spirit Part 9: ‘It Cannot Justify, It Cannot Sanctify’
 Douglas J. Moo, Encountering the Book of Romans: A Theological Survey (Grand Rapids: Baker Academic, 2002). Moo provides further depth in his Romans commentary.
 Sinclair B. Ferguson, The Holy Spirit (Downers Grove, IL: 1996), 160.
 Stephen Westerholm, Perspectives Old and New on Paul: The “Lutheran” Paul and His Critics (Grand Rapids: Wm. B. Eerdmans, 2004), 397.
 Moo, 125–6.