Short answer: most evangelicals identify the author of Romans 13:8 as the apostle Paul.

Why evangelicals accept Paul as the author
– The letter itself names Paul as the writer (Romans 1:1; 1:7; 16:22).
– Internal features fit Paul’s style and theology (themes of justification by faith, law and grace, Christian ethics, personal greetings and travel plans).
– Early Christian testimony consistently attributes Romans to Paul (Clement of Rome, Ignatius, Irenaeus, Tertullian, Origen, etc.).
– The book is well attested in the early manuscript tradition and was accepted in the early church as apostolic and authoritative, which is important for evangelical claims about Scripture’s reliability and authority.

Who Paul was (brief evangelical summary)
– A Jew from Tarsus, trained as a Pharisee under Gamaliel (Philippians 3:5; Acts 22:3).
– A Roman citizen (Acts 22:25–29).
– Initially persecuted the church, then converted after a dramatic encounter with the risen Christ on the Damascus road (Acts 9).
– Became the chief missionary-apostle to the Gentiles, undertaking several missionary journeys, planting churches, and writing letters that form much of the New Testament.
– Thought to have written Romans during his stay in Corinth (commonly dated c. AD 56–58) as he prepared for a planned visit to Spain and sought support for the work (see Romans 15).

Context and meaning of Romans 13:8 (from an evangelical perspective)
– Romans 13:8 (ESV): “Owe no one anything, except to love one another, for the one who loves another has fulfilled the law.”
– Context: Romans 12–15 moves from doctrinal exposition (chapters 1–11) into practical Christian living. Chapter 13 addresses submission to governing authorities and the Christian’s duty to love others.
– Evangelical interpretation emphasizes that “owing” is primarily about moral/relational obligation: Christians should not live in a way that burdens others with debts of duty, but they are always “indebted” to show sacrificial love. Love is presented as the fulfillment of the moral law (cf. Galatians 5:14; Matthew 22:37–40).
– The verse is read in light of Pauline theology: love is the fruit of the Spirit and the ethic flowing from justification by faith — Christians are set right with God and therefore live out that status in obedient, love-centered behavior.

Where to read more (evangelical resources)
– Commentaries: Douglas Moo (Romans, NIVAC), Thomas R. Schreiner (Baker Exegetical Commentary on the New Testament), F. F. Bruce (Tyndale New Testament Commentaries).
– Study Bibles: ESV Study Bible, NIV Study Bible.
– Classic evangelical introductions to Paul and Romans: N. T. Wright (for a broader Anglican-evangelical perspective), D. A. Carson (for Pauline theology).

If you’d like, I can provide a short devotional reflection on Romans 13:8, a more detailed exegetical note, or excerpts from an evangelical commentary. Which would you prefer?