The Universal Problem: No One Achieves Righteousness by Works

Paul’s argument that “faith is credited as righteousness” (Romans 4:3–5, quoting Genesis 15:6) is the theological cornerstone of justification by faith alone. It rests on a deliberate contrast between two systems of relating to God: works (human effort to earn merit) and faith (trusting God’s promise apart from merit). Below is the step-by-step logic as Paul develops it, primarily in Romans 3–4 and Galatians 3.

1. The Universal Problem: No One Achieves Righteousness by Works

1. Premise: “By works of the law no human being will be justified” (Rom 3:20; cf. Gal 2:16).
2. Reason: The law exposes sin, not righteousness; it demands perfect obedience, which all fail (Rom 3:23; Gal 3:10–11).
3. Conclusion: Righteousness cannot be earned; it must be received.

2. The Old Testament Witness: Abraham Believed, and It Was Credited

1. Key text: “Abraham believed God, and it was credited to him as righteousness” (Gen 15:6; Rom 4:3; Gal 3:6).
2. Timing is decisive: This crediting happened before circumcision (Gen 17) and centuries before the Mosaic law (Rom 4:9–13).
3. Therefore, righteousness by faith predates and transcends the law.
4. Nature of the act: Abraham’s “belief” was not a work that merited credit; it was empty-handed trust in God’s promise of a son despite sterility and old age (Rom 4:18–21).
5. Paul’s analogy: “To the one who does not work but believes… his faith is credited as righteousness” (Rom 4:5).

3. Accounting Logic: Imputation, Not Infusion

1. Metaphor: God treats faith like a ledger entry. The believer has no positive balance (all are debtors, Rom 3:23), yet God credits (λογίζομαι, logizomai, 11× in Rom 4) Christ’s righteousness to the account (Rom 4:6–8; cf. 2 Cor 5:21).
2. David confirms: Psalm 32:1–2 speaks of sins “not counted” (same verb); forgiveness is non-imputation of guilt + imputation of righteousness (Rom 4:6–8).

4. Christological Fulfillment: Faith’s Object Is the Risen Jesus

1. Romans 3:21–26: The righteousness God credits is “through faith in Jesus Christ” because Jesus is the propitiation (ἱλαστήριον) who absorbs wrath and the righteous one whose obedience is gifted.
2. Romans 4:23–25: Genesis 15:6 was written “for us” who believe in Him who raised Jesus, whose death was “for our trespasses” and resurrection “for our justification.”

5. Exclusion of Boasting

1. Corollary: If righteousness were by works, boasting would be valid (Rom 4:2).
2. But: “Where then is boasting? It is excluded” (Rom 3:27). Faith, by definition, looks away from self to Another; it is the anti-boast.

Summary in Paul’s Own Words

“Now to the one who works, his wages are not credited as a gift but as what is due. But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness.” (Rom 4:4–5)

In short: Faith is counted as righteousness not because it is inherently meritorious, but because it is the instrument that receives the alien righteousness of Christ, promised in the gospel and foreshadowed in Abraham. It is God’s chosen mechanism to uphold both His justice (sin is punished in Christ) and His grace (righteousness is gifted, not earned).