The Greek phrase dikaiosynē theou could be translated as the “righteousness/justice of God” and reflects one of Paul’s major theological concerns. However, it is debated how it should best be translated.
Should this be translated as a genitive of source, meaning the righteousness from God? Righteousness could be a status that is imputed to the believer through the verdict that is handed out before the divine law court or could denote the ethical transformation of the believer.This has been a major divide between traditional Protestant and Catholic interpreters.
Alternatively, it could be translated as a subject genitive, meaning that it refers to God’s own righteousness as either the deity’s moral perfection or characteristic way of acting in relation to the people who have been divinely elected. I prefer this reading. A key theme of Romans is to vindicate God’s righteousness in the equitable treatment of all humanity, the revelation of salvation through the death and resurrection of Christ, and God’s continued faithfulness to the covenant people as well as to the nations despite what Paul perceives to be the lackluster reception of his gospel among his compatriots. After all, Paul faces the objection over whether human unfaithfulness could ever nullify God’s faithfulness and replies “may it never be!” (Rom 3:3-4, see also the expressions “righteousness of God” and “truthfulness of God” in the section).