Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
Two things are presented here with respect to God; His judgment against evil the evil-doer shall not escape (the real difference of right and wrong would be maintained by judgment); and His mercy, patience, and long-suffering with regard to the evil-doer His goodness inviting him to repentance. He who continued in evil deceived himself by trying to forget the sure judgment of God and by despising His goodness. The consequences, both of a life opposed to God and to His truth on the one hand, and of the search after that which is pleasing to Him, and thereby for eternal life on the other, were sure tribulation and anguish in the one case, in the other glory and honour; and that without more respect to the Jews than to the Gentiles.
God judged things according to their true moral character, and according to the advantages which the guilty one had enjoyed. [See Note #9] Those who had sinned without law should perish without law, and those who had sinned under the law should be judged according to the law, in the day when God should judge the secrets of the heart according to the gospel which Paul preached. This character of the judgment is very important. It is not the government of the world by an earthly and outward judgment, as the Jew understood it, but that of the individual according to God's knowledge of the heart.
Also God would have realities. The Gentile who fulfilled the law was better than a Jew who broke it. If he called himself a Jew and acted ill (Rom 2:17), he only dishonoured God, and caused His name to be blasphemed among the Gentiles whilst boasting in his privileges. He then enlarges on the point that God requires moral reality, and that a Gentile who did that which the law demanded was better worth than a Jew who disobeyed it, and that the real Jew was he who had the law in his heart, being circumcised also in the spirit, and not he who had only outward circumcision. This was a condition which God could praise, and not man only.
Note #9
How strikingly this also brings out what so breaks everywhere through the doctrine of this epistle that everything is according to its reality before God, God being revealed through Christ and the cross. All must take its true character and result according to what He was. Note moreover that the terms suppose gospel knowledge "seek for glory, honour, and incorruptibility." These are known by Christianity.