For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:

For when those of the nations, which have no law, practise by nature the things of the law, these, having no law, are a law to themselves;

for when Gentiles which have no law do by nature the things of the law, these, having no law, are a law unto themselves;

For, when nations that have not a law, by nature may do the things of the law, these not having a law, to themselves are a law;

For when Gentiles who have no Law obey by natural instinct the commands of the Law, they, without having a Law, are a Law to themselves;

For when the Gentiles, who do not have the law, do by nature those things which are of the law, such persons, not having the law, are a law unto themselves.

When Gentiles, who have no Law, do instinctively what the Law requires, they, though they have no Law, are a Law to themselves;

Quum enim Gentes, quæ Legem non habent, natura quæ Legis sunt faciant, ipsæ, Legem non habentes, sibi ipsæ sunt Lex:

For when the Gentiles, etc. He now states what proves the former clause; for he did not think it enough to condemn us by mere assertion, and only to pronounce on us the just judgment of God; but he proceeds to prove this by reasons, in order to excite us to a greater desire for Christ, and to a greater love towards him. He indeed shows that ignorance is in vain pretended as an excuse by the Gentiles, since they prove by their own deeds that they have some rule of righteousness: for there is no nation so lost to every thing human, that it does not keep within the limits of some laws. Since then all nations, of themselves and without a monitor, are disposed to make laws for themselves, it is beyond all question evident that they have some notions of justice and rectitude, which the Greeks call preconceptions prolepseis, and which are implanted by nature in the hearts of men. They have then a law, though they are without law: for though they have not a written law, they are yet by no means wholly destitute of the knowledge of what is right and just; as they could not otherwise distinguish between vice and virtue; the first of which they restrain by punishment, and the latter they commend, and manifest their approbation of it by honoring it with rewards. He sets nature in opposition to a written law, meaning that the Gentiles had the natural light of righteousness, which supplied the place of that law by which the Jews were instructed, so that they were a law to themselves. [1]

Footnotes

1 - As to the phrase, "these are a law unto themselves," Venema adduces classical examples -- pan to beltiston phainomenon esto soi nomos aparabatos "Whatever seems best, let it be to thee a perpetual law." -- Epict. in Ench., c. 75. "to men orthon nomos esti basilekos What is indeed right, is a royal law." -- Plato in Min., page 317. The heathens themselves acknowledged a law of nature. Turrettin quotes a passage from a lost work of Cicero, retained by Lactantius, which remarkably coincides with the language of Paul here -- Ed.

For when - The apostle, in Romans 2:13, had stated a general principle, that the doers of the Law only can be justified, if justification is attempted by the Law. In this verse and the next, he proceeds to show that the same principle is applicable to the pagan; that though they have not the written Law of God, yet that they have sufficient knowledge of his will to take away every excuse for sin, and consequently that the course of reasoning by which he had come to the conclusion that they were guilty, is well founded. This verse is not to be understood as affirming, as an historical fact, that any of the pagan ever did perfectly obey the Law which they had, any more than the previous verse affirms it of the Jews, The main point in the argument is, that if people are justified by the Law, their obedience must be entire and perfect; that this is not to be external only, or to consist in hearing or in acknowledging the justice of the Law; and that the Gentiles had an opportunity of illustrating this principle as well as the Jews, since they also had a law among themselves. The word "when" ὅταν hotan does not imply that the thing shall certainly take place, but is one form of introducing a supposition; or of stating the connection of one thing with another, Matthew 5:11; Matthew 6:2, Matthew 6:5-6, Matthew 6:16; Matthew 10:19. It is, however, true that the main things contained in this verse, and the next, actually occurred, that the Gentiles did many things which the Law of God required.
The Gentiles - All who were not Jews.
Which have not the law - Who have net a revelation, or the written word of God. In the Greek the article is omitted, "who have not law," that is, any revealed law.
By nature - By some, this phrase has been supposed to belong to the previous member of the sentence, "who have not the law by nature." But our translation is the more natural and usual construction. The expression means clearly by the light of conscience and reason, and whatever other helps they may have without revelation. It denotes simply, in that state which is without the revealed will of God. In that condition they had many helps of tradition, conscience, reason, and the observation of the dealings of divine Providence, so that to a considerable extent they knew what was right and what was wrong.
Do the things - Should they not merely understand and approve, but actually perform the things required in the Law.
Contained in the law - Literally, the things of the Law, that is, the things which the Law requires. Many of those things might be done by the pagan, as, e. g., respect to parents. truth, justice, honesty, chastity. So far as they did any of those things, so far they showed that they had a law among themselves. And wherein they failed in these things they showed that they were justly condemned. "Are a law unto themselves." This is explained in the following verse. It means that their own reason and conscience constituted, in these things, a law, or prescribed that for them which the revealed law did to the Jews.

For when the Gentiles, which have not the law, etc. - Nor does it follow that the Gentiles who have not had a Divine revelation, shall either perish, because they had it not; or their unrighteous conduct pass unpunished, because not having this revelation might be considered as an excuse for their sins.
Do by nature the things contained in the law - Do, without this Divine revelation, through that light which God imparts to every man, the things contained in the law - act according to justice, mercy, temperance and truth, the practice of which the revealed law so powerfully enjoins; these are a law unto themselves - they are not accountable to any other law, and are not to be judged by any dispensation different from that under which they live.
Rabbi Tanchum brings in the Supreme Being as saying: When I decreed any thing against the Gentiles, to whom I have not given laws and statutes, and they know what I have decreed; immediately they repent; but the Israelites do not so. Tanchum, fol. 43. 2.

(6) For when the Gentiles, which have (i) not the law, do by (k) nature the things contained in the law, these, having not the law, are a law unto themselves:
(6) He prevents an objection which might be made by the Gentiles, who even though they do not have the law of Moses, yet they have no reason why they may excuse their wickedness, in that they have something written in their hearts instead of a law, as men do who forbid and punish some things as wicked, and command and commend other things as good.
(i) Not that they are without any law, but rather the law of the Jews.
(k) Command honest things, and forbid dishonest.

For when the Gentiles which have not the law,.... The objection of the Gentiles against their condemnation, taken from their being without the law, is here obviated. The apostle owns that they had not the law, that is, the written law of Moses, and yet intimates that they had, and must have a law, against which they sinned, and so deserved punishment, and which they in part obeyed; for these men
do by nature the things contained in the law. The matter and substance of the moral law of Moses agrees with the law and light of nature; and the Gentiles in some measure, and in some sort, did these things by nature; not that men by the mere strength of nature without the grace of God, can fulfil the law, or do anything that is acceptable to God; and indeed, what these men did was merely natural and carnal, and so unacceptable to God. Some understand this of nature assisted by grace, in converted Gentiles, whether before or after the coming of Christ; others expound the phrase, by nature, freely, willingly, in opposition to the servile spirit of the Jews, in their obedience to the law; though it rather seems to design the dictates of natural reason, by which they acted: and so
these having not the law, the written law,
are a law to themselves; which they have by nature and use, and which natural reason dictates to them. So Plato distinguishes the law
"into written and un written (q): the written law is that which was used in commonwealths; and that "which was according to custom or nature", was called unwritten, such as not to go to market naked, nor to be clothed with women's clothes; which things were not forbidden by any law, but these were not done because forbidden by the unwritten law;''
which he calls "unwritten", because not written on tables, or with ink; otherwise it was written in their minds, and which by nature and use they were accustomed to.
(q) Laertii Vit. Philosoph. l. 3. in Vita Platon.

For when the gentiles - That is, any of them. St. Paul, having refuted the perverse judgment of the Jews concerning the heathens, proceeds to show the just judgment of God against them. He now speaks directly of the heathens, in order to convince the heathens. Yet the concession he makes to these serves more strongly to convince the Jews. Do by nature - That is, without an outward rule; though this also, strictly speaking, is by preventing grace. The things contained in the law - The ten commandments being only the substance of the law of nature. These, not having the written law, are a law unto themselves - That is, what the law is to the Jews, they are, by the grace of God, to themselves; namely, a rule of life.