Yes, this is evident from the Holy Scriptures which define sin as the transgression of the law. 'Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law.' (1 John 3:4). Indeed if sin did not have a God given definition then all scriptural exhortations against sin would be meaningless.
The confessions and creeds of the Reformed churches affirm that there is a rule of obedience set out in scripture, that it is a fixed and permanent standard, and that it is given by God. This rule of obedience or standard we call the moral law, and is summarily comprehended in the Ten Commandments.
What is the Moral Law?
In his commentary on the Heidelberg Catechism, Zacharias Ursinus defines the moral law as a .."doctrine harmonising with the eternal and unchangeable wisdom and justice of God, distinguishing right from wrong, known by nature, engraved upon the hearts of creatures endowed with reason in their creation, and afterwards often repeated and declared by the voice of God through his servants, the prophets; teaching what God is and what he requires, binding all intelligent creatures to perfect obedience and conformity to the law, internal and external, promising the favour of God and eternal life to all those who render perfect obedience, and at the same time denouncing the wrath of God and everlasting punishment upon all the who do not render obedience, unless remission of sins and reconciliation with God be secured for the sake of Christ the mediator.' (Page 490-491, Commentary on the Heidelberg Catechism).
This definition raises a number of interesting points which we will discuss below:
A. The Ground of the Moral Law
The ground of this law is held to be the nature of God. The all-perfect, eternal and unchangeable nature of God.
A.A. Hodge in his Commentary on the Westminster Confession of Faith (pg 249) makes an important distinction with regard to the rightness of the moral law. " When we affirm that God is holy, we do not mean that he makes right to be right by simply willing it, but that he wills it because it is right." It is the divine nature of God that is the absolute standard of righteousness, not the subjectiveness of man's reason.
B. One Universal Rule of Law
Ursinus in his definition teaches that the moral law is eternal, which is evident from his understanding that it "harmonis[es] with the eternal and unchangeable wisdom of God." and being eternal it must therefore be and remain the same from the beginning to the end of the world. Indeed in the Scriptures there is one law that defines:
(i) the guilt of a sinner;
(ii) the obedience of Christ; and
(iii) and the holiness which believers are to pursue.
The Rev. David Silversides deals with this particular truth in his sermon, The Christian and the Law, explaining that we can see these 3 points being applied by the Apostle in Colossians 3:5-8:
“Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry: For which things' sake the wrath of God cometh on the children of disobedience: in the which ye also walked some time, when ye lived in them. But now ye also put off all these; anger, wrath, malice, blasphemy, filthy communication out of your mouth.”
The Apostle here names specific deeds that are to be mortified and does not leave sin undefined nor does he leave the Colossians to themselves to 'feel' what is right and what is sinful.
Further the Apostle teaches that the same sins to be mortified by the believer are the same sins that bring the wrath of God on the children of disobedience. One law for all.
There is one single standard or rule that defines holiness that the believer is to pursue as well as the ground of condemnation for the unbeliever. Again the sins that believers are to mortify in pursuit of holiness are those same sins that they formerly walked in as unbelievers: “in the which ye also walked some time, when ye lived in them” (Colossians 3:7). That same law which convinces an unbeliever before conversion also defines the holiness he is to pursue after it, which is confirmed by the Apostle in Romans 3:20 “Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.”
C. Known by Nature
The moral law is known by nature, and is sometimes called the natural law. If we are to make a distinction between "natural law" and "moral law" it is only in respect of their accidents and conclusions. Francis Turretin summarises these differences:
"The difference is with regard to mode of delivery. In the moral law, these duties [to God and our neighbour] are clearly, distinctly and fully declared; while in the natural law they are obscurely and imperfectly declared both because many intimations have been lost and obliterated by sin and because it has been variously corrupted by the vanity and wickedness of men (Rom: 1:20-22). Not to mention other differences: as the natural law was engraved upon the hearts of men, the moral on stony tables; the former pertains to all universally, the latter only to those called by the word; the former contains nothing except morality, the latter has also certain ceremonials mingled with it." (Institutes of Elenctic Theology, Vol 2, pages 6-7).
D. Republication of the Law
Because the natural law written on man's heart has been obscured by sin and darkened, it is clear to see why God republished that law and committed it to writing in the Ten Commandments, where the moral law is summarily comprehended.
John Brown of Haddington, in Book VI of 'A Compendious View of Natural and Revealed Religion' sets out three ways the moral law has been manifested or made known to man:
Firstly, as we have discussed above it is partly and obscurely written on the heart of all men - Rom 2:14-15 '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."
Second, it is summarily contained in the Ten Commandments, Ex 20: 3-17. For although when man was upright in nature there was no need for a publication of the law, after the fall there was only remains of this law surviving in the hearts of men and women. Indeed God was most gracious to man by republishing and establishing the moral law that would have otherwise been obliterated by sin, correcting those things that had been corrupted by the fall, and showing the necessity of a mediator on account of man's weakness to keep the law, "For Christ is the end of the law for righteousness to every one that believeth." (Rom 10:4).
Third, as largely held forth and explained in the whole Bible. Christ and his Apostles republished and further explained the moral law, vindicating it from false interpretations.
How do we know this one rule of obedience is unchangeable?
It was republished by Christ and his Apostles explained and vindicated, but was not enlarged in any way. John Brown of Haddington proves this by the following arguments:
1. It was long before perfect, 'Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the Lordyour God which I command you' Deut 4:2 and therefore incapable of being corrected, without taxing the wisdom of God who framed it.
2. Christ came not to destroy the ancient moral law but to fulfil it, 'Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.' Matt 5:17-18
3. Christ and his Apostles taught nothing more than what Moses and the prophets had done. 'Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets.' Matt 7:12.
Has the moral law been abrogated by Christ?
In respect of justification the law has been abrogated for those who are justified by faith in Christ, as the curse of the law has been removed and this is the reason why Paul in his Epistle to the believers at Rome declares, "there is no condemnation to them which are in Christ Jesus" and "ye are not under the law but under grace."
Yet the moral law is rooted in the changeless nature of God is not to be rejected by the Christian, but as affirmed by the Larger Catechism (Question 97) it is now to have a special use to the regenerate:
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.
Be ye holy for I am holy, in this the Law and the Gospel agrees.