Prior to proceeding with an exposition of each individual commandment, some matters need to be noted by way of preface.
God’s Gift of the Law to Man: The Manifestation of His Character
Just as God has created in man the knowledge of a Godhead, He has likewise given him an innate knowledge of the will of God. Both are, however, very obscure and entirely imperfect in man, and due to continual sinning they become even more obscure. The knowledge that one must abstain from evil and do that which is good remains in all men. However, what constitutes evil and good is more clearly discerned by one than by another. The most intelligent and virtuous among men neither know all that God has commanded and prohibited, nor the manner of observance. Paul himself says: “Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet” (Rom 7:7). It is as if the law of nature has been recorded in writing upon a slate, which has been wiped off with the hand so that here and there a sentence, some words, or letters are left, but the rest has become illegible. The heathen are acquainted with an occasional commandment. However, other commandments, as well as the manner in which they are to be observed, are mostly unknown to them (cf. vol. 1, ch. 1). The Lord has perfectly revealed the law of the ten commandments to His church, and partakers of the covenant are obligated to live accordingly. We must therefore not make the dim light of nature to be the judge which determines which commandments we are and are not obligated to observe. Nor ought it to be a touchstone determining whether or not they pertain to us (and are thus binding for us) simply because reason—that is, the dim light of nature—judges it to be so. Rather, it is so because God as Lawgiver commands it to be so, and we must judge by means of the law declared on Sinai what the conduct of all men (heathens as well as Christians) ought to be, as well as what sin and virtue are—all of which nature and reason should have taught them. Our reason even originates with God and He declares by means of it what His will is. Thus, the heathen must judge as to whether a matter is evil, not because their reason affirms it to be so, but because God wills it and makes His will known to them by means of their reason, that is, by means of the light of nature.
God is holy and therefore cannot but demand holiness from man. Some ordinances which God has prescribed to man have proceeded from the sovereign will of God, so that He would have been free not to have given them. Having given them, they are thus good, and man is under obligation to observe them solely because it pleases the sovereign Lawgiver. Such was the command given to Adam not to eat of the Tree of the Knowledge of Good and Evil; and the ceremonial laws were of this nature. However, as it is commensurate with the nature of God and of the reasonable creature that there be an obligation to be obedient to God and to have commandments by which the creature obey God, it likewise issues forth from the character of God that man have such commandments, as comprehended in the ten commandments, to be the measure of man’s holiness. This holiness is the image of God; that is, the harmony with the communicable attributes of God. It was therefore not possible for God—having thus created man in harmony with His holy nature—to either gift or command man contrary to His nature, so that man, created in His image, would hate Him, not serve Him or only serve Him in a physical sense, dishonor Him, and not publicly and corporately call upon and glorify Him. He could not have created the bearer of His image to be disobedient to authorities and parents, evil, immoral, and impure; either publicly or secretly rob his neighbor, harm the reputation of his neighbor, lie, and have a dissatisfied heart which seeks its fulfillment in that which is tangible. For all of this is contrary to the holy character of God, whose image the perfect nature of man bore. If man were still perfect, he would understand all this clearly; that is, that the ten commandments in their entirety, as well as individually, are not only law merely because God willed it to be so, but because the will to give such a law issued forth out of His holy character. Furthermore, it was inherently righteous that the holy God gave, and was willing to give, such laws to man created after His image. It thus follows that God, consistent with His holiness could neither relieve man from the obligation to obey, nor could He relieve him from accountability for the disobedience of a single commandment out of the ten and instead command the contrary, for then He would have denied both Himself and His holiness. Much less can any man relieve himself from his obligation toward any commandment, nor one man relieve another man, nor authorities their subjects from this obligation. If anyone were to undertake this, he would oppose God. If we were to have perfect light, then such questions as: “Why could God not have commanded this in such and such a fashion?” etc. would never arise in the heart of man, and one would observe that God has never relieved anyone from his obligation to obey any of the commandments. Whatever the corrupt intellect would issue forth in opposition to this, would then readily disappear.