The main object of this chapter is to show that the doctrine of justification by faith, which the apostle was defending, was found in the Old Testament. The argument is to be regarded as addressed particularly to a Jew, to show him that no new doctrine was advanced. The argument is derived, first, from the fact that Abraham was so justified, Romans 4:1-5; Secondly, from the fact that the same thing is declared by David Romans 4:6-8.
A question might still be asked, whether this justification was not in consequence of their being circumcised, and thus grew out of conformity to the Law? To answer this, the apostle shows Romans 4:9-12 that Abraham was justified by faith before he was circumcised, and that even his circumcision was in consequence of his being justified by faith, and a public seal or attestation of that fact.
Still further, the apostle shows that if people were to be justified by works, faith would be of no use; and the promises of God would have no effect. The Law works wrath Romans 4:13-14, but the conferring of the favor by faith is demonstration of the highest favor of God Romans 4:16. Abraham, moreover, had evinced a strong faith; he had shown what it was; he was an example to all who should follow. And he had thus shown that as he was justified before circumcision, and “before” the giving of the Law, so the same thing might occur in regard to those who had never been circumcised. In Romans 2; Romans 3, the apostle had shown that all had failed of keeping the Law, and that there was no other way of justification but by faith. To the salvation of the pagan, the Jew would have strong objections. He supposed that none could be saved but those who had been circumcised, and who were Jews. This objection the apostle meets in this chapter by showing that Abraham was justified in the very way in which he maintained the pagan might be; that Abraham was justified by faith without being circumcised. If the father of the faithful, the ancestor on whom the Jews so much prided themselves, was thus justified, then Paul was advancing no new doctrine in maintaining that the same thing might occur now. He was keeping strictly within the spirit of their religion in maintaining that the Gentile world might also be justified by faith. This is the outline of the reasoning in this chapter. The reasoning is such as a serious Jew must feel and acknowledge. And keeping in mind the main object which the apostle had in it, there will be found little difficulty in its interpretation.