Who does God justify according to Romans 3:30?

Les explains that in the Old Testament Gentiles were aliens from the commonwealth of Israel, strangers from the covenants of promise, without hope and without God. But now, since the gospel of grace, the playing field is level; the Jew has no advantage over the Gentile. Romans 3:30 declares that the one God will justify the circumcision (Jew) by faith and the uncircumcision (Gentile) through faith. Les notes some get picky about 'by faith' versus 'through faith,' but he says there is no difference. Both Jew and Gentile are saved on the same basis: faith in the finished work of the cross, and nothing can be added to it. He then moves to verse 31, asking whether we make void the law through faith.