A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
rom 4:1THE FOREGOING DOCTRINE OF JUSTIFICATION BY FAITH ILLUSTRATED FROM THE OLD TESTAMENT. (Rom. 4:1-25)
What shall we say then that Abraham, our father as pertaining to the flesh, hath found?--that is, (as the order in the original shows), "hath found, as pertaining to ('according to,' or 'through') the flesh"; meaning, "by all his natural efforts or legal obedience."
rom 4:2For if Abraham were justified by works, he hath whereof to glory; but not before God--"If works were the ground of Abraham's justification, he would have matter for boasting; but as it is perfectly certain that he hath none in the sight of God, it follows that Abraham could not have been justified by works." And to this agree the words of Scripture.
rom 4:3For what saith the, Scripture? Abraham believed God, and it--his faith.
was counted to him for righteousness-- (Gen 15:6). Romish expositors and Arminian Protestants make this to mean that God accepted Abraham's act of believing as a substitute for complete obedience. But this is at variance with the whole spirit and letter of the apostle's teaching. Throughout this whole argument, faith is set in direct opposition to works, in the matter of justification--and even in Rom 4:4-5. The meaning, therefore, cannot possibly be that the mere act of believing--which is as much a work as any other piece of commanded duty (Joh 6:29; Jo1 3:23) --was counted to Abraham for all obedience. The meaning plainly is that Abraham believed in the promises which embraced Christ (Gen 12:3; Gen 15:5, &c.), as we believe in Christ Himself; and in both cases, faith is merely the instrument that puts us in possession of the blessing gratuitously bestowed.
rom 4:4Now to him that worketh--as a servant for wages.
is the reward not reckoned of grace--as a matter of favor.
but of debt--as a matter of right.
rom 4:5But to him that worketh not--who, despairing of acceptance with God by "working" for it the work of obedience, does not attempt it.
but believeth on him that justifieth the ungodly--casts himself upon the mercy of Him that justifieth those who deserve only condemnation.
his faith, &c.--(See on Rom 4:3).
Second: David sings of the same justification.
rom 4:6David also describeth--"speaketh," "pronounceth."
the blessedness of the man unto whom the Lord imputeth righteousness without works--whom, though void of all good works, He, nevertheless, regards and treats as righteous.
rom 4:7Saying, Blessed, &c.-- (Psa 32:1-2). David here sings in express terms only of "transgression forgiven, sin covered, iniquity not imputed"; but as the negative blessing necessarily includes the positive, the passage is strictly in point.
rom 4:9Cometh this blessedness then, &c.--that is, "Say not, All this is spoken of the circumcised, and is therefore no evidence of God's general way of justifying men; for Abraham's justification took place long before he was circumcised, and so could have no dependence upon that rite: nay, 'the sign of circumcision' was given to Abraham as 'a seal' (or token) of the (justifying) righteousness which he had before he was circumcised; in order that he might stand forth to every age as the parent believer--the model man of justification by faith--after whose type, as the first public example of it, all were to be moulded, whether Jew or Gentile, who should thereafter believe to life everlasting."
rom 4:13For the promise, &c.--This is merely an enlargement of the foregoing reasoning, applying to the law what had just been said of circumcision.
that he should be the heir of the world--or, that "all the families of the earth should be blessed in him."
was not to Abraham or to his seed through the law--in virtue of obedience to the law.
but through the righteousness of faith--in virtue of his simple faith in the divine promises.
rom 4:14For if they which are of the law be heirs--If the blessing is to be earned by obedience to the law.
faith is made void--the whole divine method is subverted.
rom 4:15Because the law worketh wrath--has nothing to give to those who break is but condemnation and vengeance.
for where there is no law, there is no transgression--It is just the law that makes transgression, in the case of those who break it; nor can the one exist without the other.
rom 4:16Therefore, &c.--A general summary: "Thus justification is by faith, in order that its purely gracious character may be seen, and that all who follow in the steps of Abraham's faith--whether of his natural seed or no--may be assured of the like justification with the parent believer."
rom 4:17As it is written, &c.-- (Gen 17:5). This is quoted to justify his calling Abraham the "father of us all," and is to be viewed as a parenthesis.
before--that is, "in the reckoning of."
him whom he believed--that is, "Thus Abraham, in the reckoning of Him whom he believed, is the father of us all, in order that all may be assured, that doing as he did, they shall be treated as he was."
even God, quickeneth the dead--The nature and greatness of that faith of Abraham which we are to copy is here strikingly described. What he was required to believe being above nature, his faith had to fasten upon God's power to surmount physical incapacity, and call into being what did not then exist. But God having made the promise, Abraham believed Him in spite of those obstacles. This is still further illustrated in what follows.
rom 4:18Who against hope--when no ground for hope appeared.
believed in hope--that is, cherished the believing expectation.
that he might become the father of many nations, according to that which was spoken, So shall thy seed be--that is, Such "as the stars of heaven," Gen 15:5.
rom 4:19he considered not, &c.--paid no attention to those physical obstacles, both in himself and in Sarah, which might seem to render the fulfilment hopeless.
rom 4:20He staggered--hesitated
not . . . but was strong in faith, giving glory to God--as able to make good His own word in spite of all obstacles.
rom 4:21And being fully persuaded, &c.--that is, the glory which Abraham's faith gave to God consisted in this, that, firm in the persuasion of God's ability to fulfil his promise, no difficulties shook him.
rom 4:22And therefore it was imputed, &c.--"Let all then take notice that this was not because of anything meritorious in Abraham, but merely because he so believed."
rom 4:23Now, &c.--Here is the application of this whole argument about Abraham: These things were not recorded as mere historical facts, but as illustrations for all time of God's method of justification by faith.
rom 4:24to whom it shall be imputed, if we believe in him that raised up Jesus our Lord from the dead--in Him that hath done this, even as Abraham believed that God would raise up a seed in whom all nations should be blessed.
rom 4:25Who was delivered for--"on account of."
our offences--that is, in order to expiate them by His blood.
and raised again for--"on account of," that is, in order to.
our justification--As His resurrection was the divine assurance that He had "put away sin by the sacrifice of Himself," and the crowning of His whole work, our justification is fitly connected with that glorious act.
Note, (1) The doctrine of justification by works, as it generates self-exaltation, is contrary to the first principles of all true religion (Rom 4:2; and see on Rom 3:21-26, Note 1). (2) The way of a sinner's justification has been the same in all time, and the testimony of the Old Testament on this subject is one with that of the New (Rom 4:3, &c., and see on Rom 3:27-31, Note 1). (3) Faith and works, in the matter of justification, are opposite and irreconcilable, even as grace and debt (Rom 4:4-5; and see on Rom 11:6). If God "justifies the ungodly," works cannot be, in any sense or to any degree, the ground of justification. For the same reason, the first requisite, in order to justification, must be (under the conviction that we are "ungodly") to despair of it by works; and the next, to "believe in Him that justifieth the ungodly"--that hath a justifying righteousness to bestow, and is ready to bestow it upon those who deserve none, and to embrace it accordingly. (4) The sacraments of the Church were never intended, and are not adapted, to confer grace, or the blessings of salvation, upon men. Their proper use is to set a divine seal upon a state already existing, and so, they presuppose, and do not create it (Rom 4:8-12). As circumcision merely "sealed" Abraham's already existing acceptance with God, so with the sacraments of the New Testament. (5) As Abraham is "the heir of the world," all nations being blessed in him, through his Seed Christ Jesus, and justified solely according to the pattern of his faith, so the transmission of the true religion and all the salvation which the world will ever experience shall yet be traced back with wonder, gratitude, and joy, to that morning dawn when "the God of glory appeared unto our father Abraham, when he was in Mesopotamia, before he dwelt in Charran," Act 7:2 (Rom 4:13). (6) Nothing gives more glory to God than simple faith in His word, especially when all things seem to render the fulfilment of it hopeless (Rom 4:18-21). (7) All the Scripture examples of faith were recorded on purpose to beget and encourage the like faith in every succeeding age (Rom 4:23-24; and compare Rom 15:4). (8) Justification, in this argument, cannot be taken--as Romanists and other errorists insist--to mean a change upon men's character; for besides that this is to confound it with Sanctification, which has its appropriate place in this Epistle, the whole argument of the present chapter--and nearly all its more important clauses, expressions, and words--would in that case be unsuitable, and fitted only to mislead. Beyond all doubt it means exclusively a change upon men's state or relation to God; or, in scientific language, it is an objective, not a subjective change--a change from guilt and condemnation to acquittal and acceptance. And the best evidence that this is the key to the whole argument is, that it opens all the wards of the many-chambered lock with which the apostle has enriched us in this Epistle.