We start with an analysis of the term righteousness of God in Romans 3:21–26. The righteousness as a gift to believers (genitive of source, verses 21–22) is founded on the righteousness that characterizes his being (subjective genitive, verses 24–25). However, God’s righteousness should not always be interpreted as God’s covenantal faithfulness. For the apostle, divine righteousness brings salvation and leads to judgment, as it does in the Old Testament. There the hilastērion, the ark cover, brings these attributes together. After investigating the background, we describe Paul’s use of the image (Rom 3:25) with the help of Jewish sources. In Christ, divine justice and mercy come together in this image. Finally, we ask to whom it applies.