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: Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another; (Romans 2:14-15)
In today’s passage, Paul demonstrates how the law condemns all men, both Jew and Gentile. But how is it that the law – which was given to the Jew – can also condemn the Gentile? Paul demonstrates by the works of the Gentiles that they had some understanding of the law by the light of nature. Why? Because it was the same law which was written on the heart of Adam and on the hearts of all men in him.
Paul states that the consciences of men bear witness to the fact that they have a law – which we call natural – written on their hearts. Both their actions and the reality of a conscience bear witness against them that they are without excuse. Here, Paul establishes two witnesses as needed by biblical, positive law (Deut. 19:15). Therefore, the acts and the consciences of men are witnesses against them that they have transgressed the will of God.
This is an important point. There are attempts within modern theology – especially Reformed theology – to minimize the role of natural law in theology. This is understandable to some extent, since natural law is imperfect and cannot be understood as equal in its clarity as the written law. Yet, Paul goes on from here to demonstrate that if the Gentiles are under condemnation, how much more are the Jews when they sin; who had the moral law as revealed in the Ten Commandments at Sinai. The law written on the hearts of men by nature is equal in its content to the Ten Commandments at Sinai and is the one law of righteousness for all men, reflective of the eternal, holy character of God.
Matthew Henry comments on these verses:
[Paul] evinces that the light of nature was to the Gentiles instead of a written law. He has said (v.12) they had sinned without law, which looks like a contradiction; for where there is no law there is no transgression. But, says he, though they had not the written law (Ps. 147:20), they had that which was equivalent, not to the ceremonial, but to the moral law.
This is instructive for us for a few reasons. Firstly, when approaching those outside of Christ with the gospel, it is necessary that we point them to the fact that the brokenness of their relationship with God does not consist in a lack of information, lack of evidence, or lack of God’s providential care. The breach of the relationship is because of sin: the sin of Adam which we have all inherited. The problem the unbeliever faces is a moral one, not an intellectual one.
Secondly, because the law of nature and the law at Sinai are equivalent for the purpose of condemning sin (and since Sinai was established as a rule of holiness for that nation), it follows that the law as expressed in the Ten Commandments continues to be a rule of holiness for us today. The law shows us our sin and the Sprit brings us to repentance unto life to conform us more into the image of Christ.
As the Westminster Larger Catechism teaches us:
Q. 97. What special use is there of the moral law to the regenerate?
A. Although they that are regenerate, and believe in Christ, be delivered from the moral law as a covenant of works, so as thereby they are neither justified nor condemned; yet besides the general uses thereof common to them with all men, it is of special use, to show them how much they are bound to Christ for his fulfilling it, and enduring the curse thereof in their stead, and for their good; and thereby to provoke them to more thankfulness, and to express the same in their greater care to conform themselves thereunto as the rule of their obedience.