The Self-Donation of God, pg. 45:
"Like many Jewish apocalypticists of the first century, Paul believed that this situation can only be expected to come to a climax in a universal eschatological judgment (Rom. 2:16). If Paul had held to the typical Jewish apocalyptic perspective, wherein only those who held to the covenant by performing the works of Torah would be vindicated (with the possible exception of a few righteous Gentiles), he would necessarily have concluded that no one could be rescued from this coming judgment. If he had taken this stance, the Apostle would not have been the only Jew of this era to come to this conclusion. Such a conclusion was reached by the author of 4 Ezra. Nevertheless, unlike 4 Ezra, Paul believed that God had triumphed in Jesus. This redemption meant the overcoming of the curse of the law through the power of the divine promise of the gospel: “But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it” (3:21). Indeed this redemption came by “Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith.” (3:24-5, emphasis added). In this, God maintained his faithfulness to both to the law revealed at Sinai (and nature) and to his promise to Abraham to bless all nations through his seed: “This was to show God's righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus.” (3:25-6, emphasis added).
Even if Israel and the rest of humanity had been faithless to God through their unwillingness to give God his proper glory, God himself was by no means faithless to his unilateral promises of grace: “sin increased, grace abounded all the more” (5:20). Humanity’s faithlessness only served to show God’s even greater faithfulness and solidarity (3:1-8). As we observed in our treatment of the Old Testament, every failure on the part of Israel led to God increasing his faithfulness to his promise to Abraham. Therefore every mediator was an embodiment of God’s own deepening solidarity with his people in the face of their failure to fulfill the law. For this reason we will suggest that Käsemann’s interpretation of the “Righteousness of God” (1:17) as God’s own “salvation creating power” best fits with Paul’s argument in Romans and Galatians. It is the righteousness whereby God brings about eschatological redemption based on his prior promise to Abraham. Because of this faithfulness, God shares his own alien righteousness with sinners through Jesus Christ (1:16-7, also see Gal 3:6-9, v. 17; Phil 3:4-11)."