1) If memory serves, with perhaps quibbles about the Jew/Gentile composition in the church at Rome, your post argues similarly to Doug Moo’s Romans lengthy commentary, here on chapter 7.

For example, Moo argues that while allowing for a certain imprecision about which is husband and which wife, the law’s widow in 7:3 is the character that is free to marry Christ in v. 4, though before the second marriage is unregenerate (if I represent Moo accurately).

2) Paul uses a “paradigmatic ‘I’” also at the end of Galatians 2. Here I use H. D. Betz’s (translated) terminology “paradigmatic ‘I’” in his commentary on Galatians.

3) While granting that Paul’s use of “I” in Romans 7 transcends autobiographical use at times, it may be partly autobiographical because Paul shared both a Jewish heritage (stretching back even before Sinai) and also a conversion to Jesus Christ.

4) How can the whole world (Jew and Gentile) be held accountable to God (Rom. 3:19) on the basis of what the law says to those “under law” (here lit. “in the law” v. 18), meaning Jews? Well here “law” is especially the Psalms cited repeatedly in 3:11-18 with maybe Isaiah and Jeremiah thrown in.

Is Paul thus saying the Scriptures indict all humanity in sin? The examples in vv. 11-18 suggest they do, but the demand aspect of Mosaic law would seem in view in the phrases “in the law,” “works of the law,” and “through the law comes the knowledge of sin” in vv. 19 and 20, resp. Indictment of Gentiles would seem to follow in part at least by means of an a fortiori argument whereby Gentiles enter into at least some of the obligations of the Mosaic law (cf. Isaiah 24:5).

Gentiles are indicted because of demands placed on Jews. “For by the works of the law shall no flesh [Jew or Gentile] be justified in his sight, since through the law comes knowledge of sin” (v. 20).

5) The “brothers” in the church at Rome (7:1, 4) knew the law (7:1) yet were probably largely from “among the rest of the Gentiles” (1:13). Through faith in Jesus as wild olive shoots (ch. 11), they had entered spiritually into the family of Abraham and shared with Paul something of the experiences of the “I” of Romans 7.

Gentile Christians in Rome also “died to the law through the body of Christ” (7:4), having previous to conversion to Jesus had their sinful passions aroused by the law and been captive to the law (vv. 5,6). Or so to all appearances Paul argues despite also arguing for a fundamental distinction between Jew and Gentile, for example regarding relationship to the law of Moses (ch. 2).

6) The “I” of Romans 7 finds “delight in the law of God” (v. 22), serves the law of God with “his” mind (contrary to his flesh, v. 24), agrees with the law that it is good (v. 16), desires to do what is right (v. 18), yet is split by doing what is wrong and not desired.

Is this “I” unregenerate? Moo thinks so. Others argue for example that this is the tussle of a regenerate person before Christ or that it is the experience of the Christian in this world or that Paul is not entirely precise in defining who the “I” is.