In Romans 3, Paul draws together his arguments from the preceding chapters. “There is no difference, for all have sinned and fall short of the glory of God” (Rom 3:22b-23). “All” primarily has in view Jews and Gentiles, since his intent was to present both groups as condemned “under sin” (Rom 3:9b).
So, all people, no matter what nationality, “have sinned.” There is no ultimate “difference” between them. On judgment day, God will not ask, “Now, are you a Jew or a Gentile?” God does not show “favoritism” on that day (Rom 2:11). Paul explains what it means that all “have sinned”: all “fall short of the glory of God.” Since some Jews held the belief that Adam shared in the glory of God before the fall, Romans 3:23 declares a loss in status and position in relation to God. A “fall” has occurred. However, to “fall short” also means to not measure up, to fall short of a standard. Mankind does not measure up to the glory of God, to His perfections, His excellencies, His splendor, His majesty. This is not to imply that Adam held a pre-fall status that was somehow equal to God’s splendor and glory. Not at all. But it is to say that Adam’s pre-fall status was not unrighteousness.
To sum up: In view of God’s standard of righteousness, sinners fall short. It doesn’t matter whether they are Jews or Gentiles: “all have sinned.” Romans 3:23 reveals that, apart from Christ, everyone is in a position of unrighteousness and sin. Sobering thought.