Cranfield quotes:

Cranfield on Romans 7:7-25: “The verses which follow depict vividly the inner conflict characteristic of the true Christian, a conflict such as is possible only in the man, in whom the Holy Spirit is active and whose mind is being renewed under the discipline of the gospel. In the man who understands the law not legalistically but in the light of Christ and so recognizeds the real seriousness of its requirement, and who truly and sincerely wills to obey it, to do what is good and to avoid the evil, the man in whom the power of sin is really being seriously and resolutely challenged, in him the power of sin is clearly seen. The more he is renewed by God’s Spirit, the more sensitive he becomes to the continuing power of sin over his life and the fact that even his very best activities are marred by the egotism still entrenched within him” (p. 155).

“The acceptance of i. (=Paul’s autobiographical experience as a Christian described in Romans 7) and vii. (=the experience of Christians generally, including the very best and most mature, described in Romans 7), which has been felt by very many from early days on, is of course that the acceptance of either of them has seemed to involve altogether too dark a view of the Christian life and, in particular, to be incompatible with what is said of the believer’s liberation from sin in 6:6, 14, 17f, and 8.2. And this objection to both (i) and (vii) has seemed to a great many interpreters completely conclusive…
“With regard to the objection that it is incredible that Paul should speak of a Christian as ‘a slave under sin’s power’, we ought to ask ourselves whether our inability to accept this expression as descriptive of a Christian is not perhaps the result of failure on our part to realize the full seriousness of the ethical demands of God’s law (or of the gospel). Are we not all of us too prone still to understand them legalistically, as did the young man who could say: ‘master, all these things have I observed from my youth’? And is it not true that the more the Christian is set free from legalistic ways of thinking about God’s law and so sees more and more clearly the full splendor of the perfection towards which he is being summoned, the more conscious he becomes of his own continuing sinfulness, his stubborn all-pervasive egotism? …we may assume that Paul’s use of the first person singular throughout vv. 14-25 reflects not only his desire to state in a forceful and vivid manner what is generally true – in this case, of Christians – but also his sense of his own deep personal involvement in what he is saying” (pp. 157-159).