v1: If we condemn others, but excuse ourselves, we "have no excuse" before God. Sin is not to be explained away or excused; we must repent and enjoy God's forgiveness. God thus deals with sins in a very different way to man.
v2: It is God's prerogative to judge; not ours.
v3: God's justice; when we begin to act as God, and to pass judgment on others, we find ourselves subject to His judgment.
v4: Since repentance is our only way; God is so good to us in exposing our sins and our inner corruption. Unless God is good there can be no repentance. See Acts 11.18, where there is repentance for both Jew and Gentile.
v5-6: Our failure to repent means that we store up wrath; see also Luke 5.31-32. There is utter folly therefore in cherishing sins in our hearts. There is personal responsibility, and personal guilt; without the work of God as Saviour, we can only expect judgment. Such judgment is also totally fair, for God is utterly righteous.
v7-10: Reward for those who do good; although Paul points out later that "there is no one who does good," 3.12. No man can be saved by his works, because condemnation is universal; all the world is guilty before God, 3.19. All are naturally self-seeking, and do not obey the truth, and will be condemned. Whilst there may be an "advantage" in being a Jew (3.1; 9.4-5), all have sinned and fall short of the glory of God (3.23).
There is "eternal life", life in God for those who seek Him. Like God Himself, this life is eternal. See 2 Cor 4.17, an eternal weight of glory, for this life is not mere longevity; there are pleasures for evermore, Ps 16.11; for ever with the Lord, 1 Thess 4.17.
v11: God is even-handed; a Jew is not accepted in Christ simply because of his heritage.
v12: Those who do not have the law will still perish if they have sinned; the difference is that those who "rely on the law" (v17) will be judged by the harsh standards of the law.
v13: Righteousness under the law is by doing, not hearing.
v14-15: The door is very slightly ajar for Gentiles who do not have the law; here God demonstrates His justice and fairness; hearts and conscience and thoughts, the roots of our behaviour; it seems that God can deal directly with these people.
These verses do not answer the question, 'Can people be saved without trusting in Christ?' Rather the challenge is that, since God is consistent, we must also be godly. We have confidence if we have trusted in Christ; that is so much better than being uncertain.
Human conscience is a powerful testimony of the existence of God. Our conscience has been called God's vicegerent. In contrast, Secena referred to the conscience as the scorpion within.
But the conscience can be faulty. Our conscience can accuse us; what Tim Keller calls the self-hater; we think we can never be good enough, never capable of doing good. In contrast the conscience can defend us, what Tim Keller calls the proud person, always finding others to blame to excuse their own bad behaviour. (See Every Good Endeavour, page 211, by Timothy Keller.)
v16: The judgment of God is through Jesus Christ, John 5.22-23; thus the standard is as high as it can be.
v17-20: The Jewish problem; they had all promised to do all God's law, Ex 24.1-8; they were therefore bound to keep it. They became proud, thinking that they alone were right, the only guides to the blind; although see Jesus' words in Matt 15.14; 23.16; John 9.41.Their false personal security is based on divine privileges.
v21-24: The problem of inconsistency; so often the Jews' actions contradicted their words, and therefore the name of God is dishonoured, Is 52.5; Ezek 36.22. Knowledge of the law is useless without obedience to the law. The Lord Jesus frequently exposed and attacked Jewish hypocrisy and inconsistency.
The challenge comes to all leaders and teachers, that our lives match our words.
v25-29: Obedience better than ritual. The Jew depended on circumcision to save him; he did not realise that this was merely a sign; much as baptism is a sign for the Christian. It is nonetheless essential, being a step of obedience; 4.9-12.
Spiritual reality is not seen in the lives of many Jews; they follow ritual but do not have a changed life. Even a real Jew has the constant challenge to live a life of faithfulness and devotion to God.
We can fall into the same error, of enjoying God's things, but missing out on the life-changing encounter with God.
Paul argues that the Jew is no different from the Gentile. The great privileges granted to the Jewish nation are useless for the individual if he does not trust in Christ.
v22-23: Abraham simply believed God and he was made righteous, which is Paul's main point. His treatment of the OT narrative brings us greater challenges though. Indeed, those things were "not for him alone," they are recorded for our benefit.
v24-25: Justification is possible because of the resurrection, another impossibility; we put our trust in the One who was raised from the dead.