How should those “under grace” relate to God’s Moral Law?
Students of grace truths do well to prayerfully think through this issue. The question is: Was the Moral Law (as revealed in the Old Testament and pre-Calvary Scripture) canceled by the New Covenant?
A popular grace author criticized accountability to the moral law of God:
” ‘If we accept part of the law [the Moral Law], we must keep it all.’ Does grace lead to a lawless attitude in the Christian life? The simple answer to this question is ‘No way!’ The Christian who is truly walking in grace is not an antinomian (‘one who opposes the Law’). Grace-oriented Christians are not “Law-bashers” but, they do understand that the Law has no place in the life of the Christian (Rom. 7:4; 8:4; 1 Tim.1:9) . . . What is the function of the Law in the world today? … The Law has a definite purpose in the world today, but not in the life of the Christian. Aren’t we still supposed to try and keep the Ten Commandments today? The answer to this question is ‘No.’… “[emphasis added]
I agree that we could not keep the Moral Law to be saved, but even at conversion the Moral Law was not annulled; Christ fulfilled it on our behalf: “Therefore we conclude that a man is justified by faith apart from the deeds of the law … Do we then make void the law through faith? Certainly not! On the contrary, we establish the law” (Rom. 3:28,31).
Law and the Saint, by Arthur Pink, [linked below] and God’s Way to Holiness by Horatius Bonar, both make a convincing case that the New Testament distinguishes the unchanging moral precepts of pre-Pentecost Scriptures from the aspects of the Mosaic code which were done away with (the Ceremonial Law and Civil Law). 
Virtually all evangelicals agree that the ceremonial and civil aspects of the Law were canceled because these applied distinctively to Israel and foreshadowed Christ’s person and work. “So let no one judge you in food or in drink, or regarding a festival or a new moon or Sabbaths, which are a shadow of things to come, but the substance is of Christ” (Col. 2:16,17).
It seems that much of the confusion of the legalism versus license problem would be cleared up if we distinguish the STANDARDS of God’s moral law from the PROCESS (or dynamic) of HOW we fulfill God’s moral will in our lives.
Romans 6:14 states, “For sin shall not have dominion over you, for you are not under law but under grace.” Praise God, we are free from the law’s legal authority; it cannot condemn us. Yet Paul continues, “What then? Shall we sin because we are not under law but under grace? Certainly not!” (Rom. 6:15). What definition we can use for “sin” if not as a violation of God’s moral law? God’s Moral Law does have an educational role for everyone today; it has continuing validity as an expression of God’s righteous standards.
The Exchanged Life movement has been greatly used of God to lift the yoke of legalism and to show the way to experience the Romans chapter 8 quality of life. However, if we get one degree “off course,” there will be increasingly obvious spiritual and ethical problems.
The Sonship Course by World Harvest Mission gives the following definitions for “law” and “legalism”:
The moral law (or commandments of God) reflects the will of our Father and His character; and, therefore, paints a picture of what righteousness and likeness to Him look like. Since God is love, the law also describes what it means to practice love. For this reason, all the law can be summed up in the command to love (Matthew 22:37-39). Believers are now dead to the law’s power to punish, condemn, and separate them from God. We are no longer under its curse (Galatians 3:10-14). However, it is not the law that died. It still describes the goal toward which our Father is faithfully committed to bring us, and which we are called to earnestly seek grace to attain. Such grace is essential because the law continues to be a perfect and impossible standard, and because it has no power to change us or produce the love it requires. Only the gospel is able to do that.
Legalism is a misunderstanding of the true nature of the law and the gospel. At its core, it is a confidence in our own righteousness, our own ability to do what is right in order to be acceptable, worthy, and declared “good” by God and others (see Luke 18:9ff., for example). It is not the pursuit, even passionately, or any given law(s) that defines something or someone as legalistic, but the hoping in the law to do what only the gospel can do. Legalism misunderstands the law by trivializing its demands as something achievable in human strength. And it misunderstands the gospel by trivializing its power to secure the righteousness for which we long. Legalism, though in often-subtle ways, says, “The law is ‘do-able’, and if you just do it, you will be all right”. Since our flesh is desperately proud, independent, and self-righteous, we are instinctively drawn to legalism like a magnet. Apart from the work of the Spirit, we will drift in that direction (see also license). 
Consider these New Testament warnings about “pulling up all the stakes” regarding the Moral Law:
“For certain men have crept in unnoticed, who long ago were marked out for this condemnation, ungodly men, who turn the GRACE of our God into lewdness and deny the only Lord God and our Lord Jesus Christ” (Jude 1:4).
“Whoever commits sin also commits lawlessness, and sin is lawlessness” (1 John 3:4).
“If you really fulfill the royal law [the law of love summarizes and includes the moral law] according to the Scripture, ‘You shall love your neighbor as yourself,’ you do well; but if you show partiality, you commit sin, and are convicted by the law as transgressors. For whoever shall keep the whole law, and yet stumble in one point, he is guilty of all. For He who said, ‘Do not commit adultery,’ also said, ‘Do not murder.’ Now if you do not commit adultery, but you do murder, you have become a transgressor of the law. So speak and so do as those who will be judged by the law of liberty” (James 2:8-12).
[Jesus declared] “Do not think that I came to destroy the Law or the Prophets. I did not come to destroy but to fulfill. For assuredly, I say to you, till heaven and earth pass away, one jot or one tittle will by no means pass from the law till all is fulfilled” (Matt. 5:17,18).
This illustration our Lord uses implies a continuation of moral law beyond Pentecost. In fact, He applies and expands the commandments in the Sermon on the Mount. In the Great Commission, the apostles are commanded to pass on to us (in this age of grace) all that Christ commanded for His people.
The denial of the law’s validity is identified by the term “antinomianism.” Crassly put, it’s the attitude,”…Let us eat and drink, for tomorrow we die!” It is rare for a confessing evangelical to go that far, but dismissing the moral law is heading that direction. The apostle Paul responded, “Do not be deceived: ‘Evil company corrupts good habits.’ Awake to righteousness, and do not sin; for some do not have the knowledge of God. I speak this to your shame” (1 Cor. 15:32-34)”
If one pursues a hyper-dispensational view, limiting God’s prescriptive will to the New Testament letters (which would exclude water baptism, etc., for the believer today), there are still plenty of commands (Greek imperatives in the original wording of the epistles) where the Christian is “under” (accountable to) commands (law).
In zeal to avoid legalism some promote license. Those who are well-studied in God’s Word and fully devoted to the Lord may not backslide, but wrong teaching will reap what is sows in the following generations. Accurate doctrine is vital to support righteous living. Notice the pattern of doctrine, followed by application in the New Testament letters (Eph. 1-3,4-6; Col. 1-2, 3; Rom. 1-11, 12-16).
Love fulfills the law, but this refers to its motive and summary character. Without the educational revelation of Moral Law, “love” can be reduced to sentimentality and subjective standards.
The Spirit-filled life fulfills the Moral Law: ” …that the righteous requirement of the law might be fulfilled in us who do not walk according to the flesh but according to the Spirit” ( Rom. 8:4). Instead of canceling the moral law, the Holy Spirit (who revealed it in our consceince and in the Scriptures) accomplishes this quality of life through us (Gal 5:16). The law is not “over” us in the sense of being able to condemn us, but it is in us, written on our hearts (Rom 7:22), and it is beside us as a standard, objectively identifying sin (2 Tim. 3:16).
As we are to avoid legalism, we also must avoid the opposite error — license. The Sonship Course adds,
License is also a misunderstanding of the true nature of the law and the gospel. At its core, it is a flippancy, apathy, and disdain for the law. Ironically, license shares the same sources as legalism. It is similarly proud, and independent; only expressing it by resting in a self-law (autonomy) instead of pursuing God’s laws heartily. Further, license likewise looks to be right by its own definition, and through its own sources. So, surprisingly enough, it is as self-righteous as legalism! License misunderstands the law by trivializing its role as the extension of the very heart of God. And it misunderstands the gospel by trivializing its goal-oriented intention to radically transform us. Paul, who challenged the Galatians’ unbelief with the truth that the Gospel is powerful enough to change God’s attitude toward us, and to stop trusting in the law for it; also challenged the Cretans unbelief in his letter to Titus with the truth that the gospel is powerful enough to change our attitude toward God as well (e.g., 2:11-12), and to seek the obedience of faith (cf. Romans 1:5). As surely as we drift off course toward legalism, we also drift off course toward license. The true gospel, which frees us from being under the law, yet changes us to be more and more like the lovers the law describes, is the compass we need to guide our path every day. 
What about Scriptures like 1 Timothy 1:8-11?
“But we know that the law is good if one uses it lawfully [here’s the challenge!], knowing this: that the law is not made for a righteous person, but for the lawless and insubordinate, for the ungodly and for sinners, for the unholy and profane, for murderers of fathers and murderers of mothers, for manslayers, for fornicators, for sodomites, for kidnappers, for liars, for perjurers, and if there is any other thing that is contrary to sound doctrine, according to the glorious gospel of the blessed God which was committed to my trust.”
Commenting on this passage, Albert Barnes accurately noted,
It cannot be supposed, moreover, that the apostle meant, to say that the [moral] law was not binding on a righteous man, or that he was under no obligation to obey it–for he everywhere teaches that the moral law is obligatory on all mankind. To suppose also that a righteous man is released from the obligation to obey the law, that is, to do right, is an absurdity…The meaning seems to be, that the purpose of the law was not to fetter and perplex those who were righteous, and who aimed to do their duty and to please God, It was not intended to produce a spirit of servitude and bondage. As the Jews interpreted it, it did this, and this interpretation appears to have been adopted by the teachers at Ephesus, to whom Paul refers. The whole tendency of their teaching was to bring the soul into a state of bondage, and to make religion a condition of servitude. Paul teaches, on the other hand, that [Biblical] religion was a condition of freedom, and that the main purpose of the law was not to fetter the minds of the righteous by numberless observances and minute regulations, but that it was to restrain the wicked from sin. This is the case with all law. No good man feels himself fettered and manacled by wholesome laws, nor does he feel that the purpose of law is to reduce him to a state of servitude. It is only the wicked who have this feeling–and in this sense the law is made for a man who intends to do wrong. 
Here the apostle refers to the role of the Mosaic law as a whole, including the moral law, as a “schoolmaster that brings us to Christ” (Gal. 3:24). It also has this role with believers. When we try to sanctify ourselves by keeping the moral law by self-effort (apart from the Christ-centered, grace-oriented, Holy Spirit-empowered living) we will become utterly frustrated (Rom. 7:24).
But does this mean that the moral law has been canceled? No! Are not all people accountable to it? Yes!
What about 1 Corinthians 10:23? “All things are lawful for me, but not all things are helpful; all things are lawful for me, but not all things edify.” The original text had no punctuation, so it must be supplied by the grammar or context. Here Paul is quoting common phrases about the beliver’s freedom from the dietary laws of the Old Testament and the issue of meat offered to idols (1 Cor. 10:14-31). ” ‘All things are lawful for me,’ but not all things are helpful”
Speaking of his missionary strategy to reach Gentiles, Paul declared, “to those who are without law, [I relate] as without law (not being without law toward God, but under law toward Christ), that I might win those who are without law. I have become all things to all men, that I might by all means save some” (1 Cor. 9:21-22).
We must not “go beyond what is written” (1 Cor. 4:6) by rejecting the references in the New Testament to the ongoing validity of God’s moral law. God’s moral precepts correspond to His righteousness and therefore remain constant. The Moral Law does not become void because God’s character is unchangeable. “Jesus Christ is the same yesterday, today, and forever” (Heb. 13:8).
As noted earlier, the method and means of doing the will of God (including His moral law) is a different issue. It is well said, “The Sermon on the Mount is really the Life on the Mount.”
We may wonder if accepting the validity of God’s moral law lowers our standard from that of Christ. Perhaps we could compare the moral law to a silhouette. Fuller light in the New Testament gives more detail to the standards of God’s ethical will for us. This will of God was perfectly shown and provided in Christ, the Person Whom the “silhouette” merely outlines. As we abide in Christ, the Holy Spirit bears the fruit of righteousness in our lives (John 15:1-8; Gal 5:16). However, Christ’s finished work and new covenant do not nullify or erase the objective “outline” image of moral law that was previously given.
This quote by A.W. Tozer is an example of a safe and wise approach to discerning truth in devotional writers:
“For myself, I am reverently concerned that I teach nothing but Christ crucified. For me to accept a teaching or even an emphasis, I must be persuaded that it is scriptural and altogether apostolic in spirit and temper. And it must be in full harmony with the best in the historic church and in the tradition marked by the finest devotional works, the sweetest and most radiant hymnody and the loftiest experiences revealed in Christian biography… To speak of the “deeper life” is not to speak of anything deeper than simple New Testament religion. Rather it is to insist that believers explore the depths of the Christian evangel for those riches it surely contains but which we are as surely missing.” 
 See a chapter excerpt from Law and the Saint by Arthur Pink. ( also available at www.ccel.org )
 Sonship: Discovering Liberty in the Gospel As Sons and daughters of God. (Appendix A: Key Concepts) World Harvest Mission Training Program www.whm.org
 Albert Barnes, New Testament Commentary (1 Timothy)
 A. W. Tozer, Keys to the Deeper Life