It was not through the law that Abraham and his offspring received the promise that he would be heir of the world, but through the righteousness that comes by faith. For if those who depend on the law are heirs, faith means nothing and the promise is worthless, because the law brings wrath. And where there is no law there is no transgression.
Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham’s offspring—not only to those who are of the law but also to those who have the faith of Abraham. He is the father of us all.
These verses surmise Paul’s argument to Gentile Christians that they have a common ancestry with Jews, and that this common ancestry, the basis for justification by faith, unites them despite their cultural differences. Abraham believed God’s promises, and that’s what justified him before God. Because Abraham was justified by faith, not works of the law, then we are all children of Abraham, because both Jews and Gentiles can be justified by faith.
Abraham’s belief was more than mere cognitive assent to a fact. God made Abraham a life-changing promise. Not only would he conceive in his old age, but his progeny would become as numerous as the stars and would inherit a large kingdom. Abraham believed God; therefore, he trusted and obeyed Him. Belief is the foundation for living and ultimately of action. But are we justified by those actions, by our works? No.
The following logic flow simplifies Paul’s argument in Romans 4:13-16. Those who depend on the law for their justification are not heirs, because the law brings wrath, because all men sin:
- Given: All men transgress the moral law.
- If law is the basis of justification, we’re not justified.
- If we’re not justified, we receive God’s wrath.
- If we receive God’s wrath, the promise is nullified.
- Therefore, if law is the basis of justification, the promise is nullified.
- But the promise is not nullified (e.g., Numbers 23:19: “God is not human, that he should lie, not a human being, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill?”).
- Therefore, we are justified not by law, but “by faith so that it may be by grace” (see Abraham).