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 2:4THE JEW UNDER LIKE CONDEMNATION WITH THE GENTILE. (Rom. 2:1-29)
the goodness of God leadeth thee to repentance--that is, is designed and adapted to do so.
rom 2:5treasurest up unto thyself wrath against--rather "in."
the day of wrath--that is wrath to come on thee in the day of wrath. What an awful idea is here expressed--that the sinner himself is amassing, like hoarded treasure, an ever accumulating stock of divine wrath, to burst upon him in "the day of the revelation of the righteous judgment of God!" And this is said not of the reckless, but of those who boasted of their purity of faith and life.
rom 2:7To them who, &c.--The substance of these verses is that the final judgment will turn upon character alone.
by patient continuance in well-doing, &c.--Compare Luk 8:15 : "That on the good ground are they, which in an honest and good heart, having heard the word, keep it, and bring forth fruit with patience"; denoting the enduring and progressive character of the new life.
rom 2:8But unto them that are contentious, and do not obey the truth, &c.--referring to such keen and determined resistance to the Gospel as he himself had too painfully witnessed on the part of his own countrymen. (See Act 13:44-46; Act 17:5, Act 17:13; Act 18:6, Act 18:12; and compare Th1 2:15-16).
indignation and wrath--in the bosom of a sin-avenging God.
rom 2:9Tribulation and anguish--the effect of these in the sinner himself.
rom 2:10to the Jew first--first in perdition if unfaithful; but if obedient to the truth, first in salvation (Rom 2:10).
rom 2:12For as many as have sinned--not "as many as have sinned at all," but, "as many as are found in sin" at the judgment of the great day (as the whole context shows).
without law--that is, without the advantage of a positive Revelation.
shall also perish without law--exempt from the charge of rejecting or disregarding it.
and as many as have sinned in the law--within the pale of a positive, written Revelation.
shall be judged by the law--tried and condemned by the higher standard of that written Revelation.
rom 2:13For not the hearers, &c.--As touching the Jews, in whose ears the written law is continually resounding, the condemnation of as many of them as are found sinners at the last involves no difficulty; but even as respects the heathen, who are strangers to the law in its positive and written form--since they show how deeply it is engraven on their moral nature, which witnesses within them for righteousness and against iniquity, accusing or condemning them according as they violate or obey its stern dictates--their condemnation also for all the sin in which they live and die will carry its dreadful echo in their own breasts.
rom 2:15their thoughts the meanwhile accusing or else excusing--that is, perhaps by turns doing both.
rom 2:16In the day, &c.--Here the unfinished statement of Rom 2:12 is resumed and closed.
shall judge the secrets of men--here specially referring to the unfathomed depths of hypocrisy in the self-righteous whom the apostle had to deal with. (See Ecc 12:14; Co1 4:5).
according to my gospel--to my teaching as a preacher of the Gospel.
rom 2:17Behold--"But if" is, beyond doubt, the true reading here. (It differs but in a single letter from the received reading, and the sense is the same).
rom 2:18approvest the things that are excellent--"triest the things that differ" (Margin). Both senses are good, and indeed the former is but the result of the latter action. (See on Phi 1:10).
rom 2:20hast the form of knowledge and of the truth in the law--not being left, as the heathen are, to vague conjecture on divine things, but favored with definite and precise information from heaven.
rom 2:22thou that abhorrest idols--as the Jews did ever after their captivity, though bent on them before.
dost thou commit sacrilege?--not, as some excellent interpreters, "dost thou rob idol temples?" but more generally, as we take it, "dost thou profane holy things?" (as in Mat 21:12-13, and in other ways).
rom 2:24as it is written--(See Isa 52:5, Marginal reference).
rom 2:25For circumcision--that is, One's being within the covenant of which circumcision was the outward sign and seal.
verily profiteth, if thou keep the law--if the inward reality correspond to the outward sign.
but if, &c.--that is, "Otherwise, thou art no better than the uncircumcised heathen."
rom 2:26Therefore if the uncircumcision keep the . . . law, &c.--Two mistaken interpretations, we think, are given of these words: First, that the case here supposed is an impossible one, and put merely for illustration [HALDANE, CHALMERS, HODGE]; second that it is the case of the heathen who may and do please God when they act, as has been and is done, up to the light of nature [GROTIUS, OLSHAUSEN, &c.]. The first interpretation is, in our judgment, unnatural; the second, opposed to the apostle's own teaching. But the case here put is, we think, such as that of Cornelius (Acts 10:1-48), who, though outside the external pale of God's covenant, yet having come to the knowledge of the truths contained in it, do manifest the grace of the covenant without the seal of it, and exemplify the character and walk of Abraham's children, though not called by the name of Abraham. Thus, this is but another way of announcing that God was about to show the insufficiency of the mere badge of the Abrahamic covenant, by calling from among the Gentiles a seed of Abraham that had never received the seal of circumcision (see on Gal 5:6); and this interpretation is confirmed by all that follows.
rom 2:28he is not a Jew which is one outwardly, &c.--In other words, the name of "Jew" and the rite of "circumcision" were designed but as outward symbols of a separation from the irreligious and ungodly world unto holy devotedness in heart and life to the God of salvation. Where this is realized, the signs are full of significance; but where it is not, they are worse than useless.
Note, (1) It is a sad mark of depravity when all that is designed and fitted to melt only hardens the heart (Rom 2:4, and compare Pe2 3:9; Ecc 8:11). (2) Amidst all the inequalities of religious opportunity measured out to men, and the mysterious bearing of this upon their character and destiny for eternity, the same great principles of judgment, in a form suited to their respective discipline, will be applied to all, and perfect equity will be seen to reign throughout every stage of the divine administration (Rom 2:11-16). (3) "The law written on the heart" (Rom 2:14-15) --or the Ethics of Natural Theology--may be said to be the one deep foundation on which all revealed religion reposes; and see on Rom 1:19-20, where we have what we may call its other foundation--the Physics and Metaphysics of Natural Theology. The testimony of these two passages is to the theologian invaluable, while in the breast of every teachable Christian it wakens such deep echoes as are inexpressibly solemn and precious. (4) High religious professions are a fearful aggravation of the inconsistencies of such as make them (Rom 2:17-24). See Sa2 12:14. (5) As no external privileges, or badge of discipleship, will shield the unholy from the wrath of God, so neither will the want of them shut out from the kingdom of heaven such as have experienced without them that change of heart which the seals of God's covenant were designed to mark. In the sight of the great Searcher of hearts, the Judge of quick and dead, the renovation of the character in heart and life is all in all. In view of this, have not all baptized, sacramented disciples of the Lord Jesus, who "profess that they know God, but in works deny Him," need to tremble--who, under the guise of friends, are "the enemies of the cross of Christ?"