We open up with Question 93: What is the moral law?
The moral law is the declaration of the will of God to mankind, directing and binding every one to personal, perfect, and perpetual conformity and obedience thereunto, in the frame and disposition of the whole man, soul and body, and in performance of all those duties of holiness and righteousness which he oweth to God and man: promising life upon the fulfilling and threatening death upon the breach of it.
First clause then, the moral law is the declaration of the will of God to man:
The presupposition of Christian ethics is that God has revealed His will to mankind which is to be the standard and rule of man's moral actions and thoughts. This verbal revelation or declaration of the will of God is God's moral law written in the Bible....The point is that Biblical Law is Gods Law; it is God's revealed will in words and sentences which God spoke to Moses (ad the prophets and apostles) and which Moses (and the prophets and apostles) recorded under the inspiration of the H0ly Spirit, so that Biblical Law is the revealed will of God for mankind. (538)
We have learned in our study of the Catechism dealing with God's perfections that God is His perfections. Evert Divine perfection is identical with God's Being...Whatever God is, He is completely, simultaneously, consistently, perfectly and eternally...Therefore God's Will is one with God's Being. (539-540)
It is for these reasons that the law of God is called the testimony of the LORD (Ps. 19:7), because it testified to God's character of which it is a written description. Being "the transcript" of God's holy character and will for mankind, it is a perfect guide for all thought and behavior: "The law of the LORD is perfect" (Ps. 19:7).... (540)
"We are not autonomous. That is, we may not live according to tour own law. The moral condition of humankind is that of heteronomy: we live under the law of another. The specific form of heteronomy under which we live is theonomy, or the law of God." 38. Sproul,Essential Truths of the Christian Faith, 17-18. (541)
Because God our Creator, Sovereign and Redeemer DIRECTS all His image-bearers to live according to His revealed will, it is humankind's BINDING DUTY to submit to and obey that divinely revealed will. (541)
Therefore, obedience to Biblical La must begin with saving faith in Jesus Christ, for our obedience to the Las is not accepted with God outside of Christ (Rom. 8:1-4). Even after we become Christians, our obedience is not accepted by God because of any inherent qualities in it, but solely because of the merits of Jesus Christ in whose grace we stand before God (Rom. 5:10). (543)
(1) Our believing obedience to God's Law must be personal. That obedience God requires of us must be preformed by us. It cannot be done by another in our name or on our behalf....Furthermore, the obedience which Christ has performed for us, does not exempt us from our obligation to yield sincere obedience to God's law. (543)
(2) Our believing obedience must be perfect. The same obligation Adam had in the beginning--to yield perfect obedience to God, remains in force today, although we are not able in this life to perfectly obey God's Law. This is not to imply that we obey the Law as a Covenant of Works; rather, we obey it as the rule of obedience for our lives motivated by love for Christ for saving us from our sins. (544)
To be perfect our obedience must be from the heart and not merely external...Furthermore, perfect obedience is universal obedience, i.e., it does not pick and choose which moral laws of God it will obey...And, as we have seen it must be evangelical obedience, arising from faith in Christ, performed not to merit God's favor, but rendered out of gratitude and the desire to please God. We must not attempt to perform i in our own strength, but in the power of the Spirit and all our obedience must be rendered with a proper sense of our imperfections. (544-545)
(3) Our believing obedience must be perpetual, "without backsliding from God, or the least remissness in our duty to Him..."
(4) Our believing obedience must be in conformity and obedience to the revealed will of God in the Bible. Obedience to God is obedience to specific commands given by God in the Bible. (545)
Obedience to God's Law is obedience of the whole person, soul and body, External obedience in the behavior of the persons body without the involvement of a sincere heart is condemned by Christ... (547)
"God is not satisfied with outward forms of religion. He has not only ordered man's material existence but as also created his inner life and soul. He is therefore the rightful Lord of man's spiritual life, and for this reason man must serve Him in an inward and spiritual manner through purity of heart, devotion, love and holiness." 51. Norval Geldenhuys, New International Commentary on the New Testament: Commentary on the Gospel of Luke (Grand Rapids, MI: Wm. B. Eerdmans  1966), 341 (547-548)
However, although obedience to God must originate with the heart, it nevertheless will include the body and physical behavior. (549)
Carefulness and strictness in our outward behavior is the manifestation of carefulness and strictness in our inward, spiritual and mental frame of mind and disposition. In other words, obedience must be obedience of the whole person, otherwise obedience is hypocrisy. (550)
Catechism Q. 93 makes the point that the Law of God binds everyone, and especially Christians, to obedience in the performance of all those duties of holiness and righteousness which he owes to God and man. Holiness describes the nature o our relationship and duties to God, and righteousness describes the nature of our relationship and duties to other human beings. (551)
We are righteous when our actions and dispositions toward other human beings, in the various relationships we have with each other in human society, are in careful conformity to what God commands us regarding how are to relate to one another in love and justice. (551)
The Magnificat and the Benedictus make clear that the salvation Jesus brings is COMPREHENSIVE. Because the effects of sin are comprehensive, salvation from sin is comprehensive. (552)
Question 93 concludes by saying that the Law of God promises life upon the fulfilling of it and threatens death upon the breach of it. (556)
This promise of life upon obedience and threat of death upon disobedience are generally referred to as the sanctions of the Law...Sanctions are the Law's teeth, without them laws are mere suggestions...As Puritan Anthony Burgess picturesquely states it: "The tame horse needth a spur, as well as the broken colt." 67. KEvan, The Grace of Law, 187. (556)
The reasons for these curses and blessings annexed to God's demands is that even in the believer much sins remains, and he needs many "goads" to keep him on the straight and narrows...And "[i]f we have respect to all the commandments, and labour faithfully to keepe them...then shall wee constantly enjoy all those blessing and graces which God hath promised to his righteous servants." 71. John Dod, quoted in Kevan, The Grace of Law, 189. (557)
God's promised rewards for faithfulness to His Law are all of grace, far more than we deserve...."The reward is bestowed 'for the faithfulnesse of the Promiser, not for the desert of the worke,' and thus it is that 'the Lord will richly of His free grace reward these workes with glory and happinesse in His Kingdome' although 'the strength of our title stand upon God's free gift [John Downame]." 72. Kevan, The Grace of Law, 190 (557-558)
After having said that God promises certain blessing to those who obey His Law, it must be understood that the true believer, while he enjoys God's blessings at heart, obeys God's Law because He loves God. (558)
At the same time the believer does not dismiss all love of divine and gracious rewards as if such love was evidence of a "mercenary spirit". There is nothing unchristian about hoping for a promised reward from God. (558)
Is there any use of the moral law to man since the fall? Although no man, since the fall, can attain to righteousness and life by the moral law; yet there is great use thereof, as well common to all men, as peculiar either to the unregenerate or the regenerate.
There are three sections in this section, a) the use of the Law before the fall, b) the non-use of the Law since the fall, and c) the great use of the Law since the fall. I'm going to run the quotations from these three into one long string...
A] Before Adam's fall into sin, the Law of God was the means by which Adman would obtain unloseable life and indefectible holiness... (559)
B] Since the fall of the human race into sin, human beings cannot attain to unloseable eternal life and indefectible holiness by means of obedience to God's Law--a man is not justified by the works of the Law but through faith in Christ Jesus. The reasons that eternal life is through faith in Christ and not by obedience to Law is explained in Romans 8:3: "For what the Law could not do, weak as it was through the flesh, God did, sending His own Son." The Law of God commands and condemns but it cannot forgive justify, remove the condemnation of sin nor destroy the tyrannical power of sin over the sinner. It can promote and guard life once given to the believer by grace; but the Law cannot give life. It is impotent to justify or regenerate or liberate from sin because of the depravity of spiritual deadness of fallen man's sinful nature. (560)
C] Although life and righteousness cannot be attained by the Law of God since the Fall, yet there is great use thereof to all human beings without exception. ...
First, it is possible to apply the Law of God unlawfully.
"[T]he law becomes anything but good to those who misuse it. It becomes a burden too heavy to bear....Christ delivers the sinner, not from the spiritual obligations of God's holy Law, but from the evil that he has brought upon himself by his misuses of the Law. Man's fundamental abuse of the Law is to put it into opposition to Christ for justification, and to regard Law-keeping as an alternative ground of acceptance before God. 77. Ernest F. Kevan, The Moral Law (God's Law) (Pennsylvania: Sovereign Grace Publishers, 1963), 16.
Second, when the Law of God is applied lawfully it is of great use to everybody. ...
Third, the Law of God and the Gospel of Christ are in full agreement. Disobedience to the Law of God and the unlawful use of God's Law are both contrary to sound teaching, according to the glorious gospel of the blessed God....
In fact the Law of God has a variety of functions in the life of the human race. It offers abundant blessings and has a wide range of practical uses. This multi-functional nature of God's Law is important to bear in mind when we consider that "the Law has become our tutor to lead us to Christ....But now that faith has come, we are no longer under a tutor," i.e. God's Law (Gal. 3:24-25). This verse, often used wrongly to show that the Christian is no longer under Biblical Law, speaks of only one of the many functions of God's Law. (561-564)