In Paul’s mind the more sin we can demonstrate the more grace can be discovered. If sin marched into the room after Torah, grace chased sin (and Torah?) out the backdoor!
“But where sin increased, grace increased all the more” (Rom 5:20b).
Sin dominated the scene through the presence of death. Grace, however, triumphs over death through righteousness and eternal life in Christ.
Again, if Torah effectively undid Jewish privilege, then grace overwhelms that undoing and creates in Jesus Christ the promise God had always planned for Israel. We can take “righteousness” in 5:21 to mean “justification before God” or “new creation life in Christ for the believer” or we can take it to refer to (as does Wright) “Jesus’ own righteous life.” In my estimation, the contextual federal emphasis of all things being in Adam and or in Christ clearly favors the latter interpretation. Righteousness comes through Jesus Christ — in him and in attachment to him.
We should probably avoid the summary ideas that what we have here is the principle of sin and the principle of grace; sin gets us death and grace gets us life. No, we are dealing here with more particular (and better) ideas: Torah dealt death to the Jewish nation and Jesus Christ deals grace to the same, providing for them triumph over death in Christ.
What then of the Gentile? They’ve been take care of, and they’ll be taken care of: both are taken care of in Christ. In the first instance, though, we do need to ask if the Gentile is in view here.