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We are sure that the definition of sin did not change for the Christian at conversion.

The apostle Paul taught that all the world is guilty before God, because all have sinned (Romans 3.19). God’s moral law is the standard that God holds all mankind to. This is the moral standard that we fall short of when we sin (Romans 3.23).

This is bad news. The worst of all bad news for the sinner is—the righteous God holds sinners accountable to his moral law, and therefore we are under condemnation to Hell for their sin, unless we are saved.

For the sinner who turns to the Lord Jesus Christ, God’s only begotten Son, whom God sent into the world to save sinners—“There is therefore now no condemnation to them which are in Christ Jesus” (Romans 8.1). Jesus has saved us from our sins and from what we deserve (Matthew 1.21).

Paul describes the state of the saved person as being “not under law but under grace” (Romans 6.14). We are no longer under condemnation for disobedience to the law,1 because in Christ “we have redemption through his blood, even the forgiveness of sins” (Colossians 1.14). We are now “justified freely by his grace through the redemption that is in Christ Jesus” (see Romans 3.24-26).

Some Christians think that, since they are Christians, they don’t need to be concerned with any part of the Law of Moses. They don’t think of it as containing the moral standard that they ought to keep. They say that, seeing that the true Christian is not under the law, therefore they (and we) should have nothing whatever to do with it.2

They speak of being released from the obligation of keeping the Old Covenant’s commandments. But when it comes to the realities of Christian living, they don’t really mean that being “not under law” gives them freedom to sin!

It is not that they intend to be lawless, or immoral. For it is not in the new nature of the Christian to condone sin—i.e. to do what is against the moral law of God. But rather, he or she will repent of sin.

Reformed Christians, of course, totally agree that we are not under the law: we are not under the law (the Old Covenant) as a covenant of works.2 However, we do understand that as Christians, we still ought to learn and keep God’s commandments—not in order to earn salvation, but as saved people who desire to live a life that is pleasing to God.

But they say that, as Christians, instead of studying the moral law in order to live according to its precepts,3 we should rather “walk in the Spirit” in order to bear the “fruit of the Spirit”. And in that way, we will not fulfil the lusts of our flesh but mortify them (compare Romans 8.1-13; Galatians 5.16-26).

The apostle John, however, teaches that the very definition of sin is whatever is against God’s moral law: “Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law” (1 John 3.4).

So, can these Christians not agree with us when we likewise define sin as any lack of conformity to, or transgression of, the (moral) law of God?4 We affirm that sin is doing, saying or thinking what God forbids, and not doing, saying or thinking what he requires5—in his moral law. So it makes sense for us to learn God’s moral law and for it to be the moral standard that we seek to keep as Christians.

Of course, they do agree. But they don’t like to involve the laws of the Old Testament, unless they are repeated somewhere in the New Testament. Whereas we are sure that the definition of sin did not change for the Christian at his or her conversion.

Therefore, even in their endeavour to avoid sin by “walking in the Spirit”, they will find themselves heading towards non-transgression of the moral law—the same law as is summed up in the Ten Commandments. That is to say, in practice they increasingly become moral law-keepers! But here is where they hold up their hand in anguish at such a thought, saying, “No, you’ve got it all wrong! But what we as Christians should want to do is fulfil the law of Christ” (compare Galatians 6.2).

If Christians are not free not to keep God’s moral commandments, and if Christians should learn and obey God’s moral commandments, then what does Paul mean in his teaching that we are “not under law but under grace” (Romans 6.14)?

By the phrase “the law,” as often used by Paul, Reformed Christians have understood that he means the covenant of life (also known as the covenant of works) that God established with Adam, and all his posterity in Adam. This same law has continued as a perfect rule of righteousness for mankind; and as such it was delivered by God to Moses on Mount Sinai, in the Ten Commandments.6

The Ten Commandments (the “two tables of the law”) were the foundation of the Old Testament (Old Covenant) that God established the people of Israel under Moses who was their leader, priest and prophet (Exodus 20; 24; Deuteronomy 4.13, 23-31).

So, we say that we are “not under the law” in this covenantal sense, because we are in the New Covenant (the covenant of grace) in Christ. And in Christ “we have redemption through his blood, even the forgiveness of sins” (Colossians 1.14).

Yes, we agree, Christians are led by the Holy Spirit, and we are not under the broken covenant of life (“the law”) any more (Galatians 5.18). But this in no way means that the moral law has ceased to remain a perfect rule of righteousness for us as Christians.


  1. All mankind is born in Adam under the law of God—in what we call the “covenant of life” or “covenant of works”. Christians are those people who have been transferred to the covenant of grace in Christ. 

  2. See the Westminster Confession of Faith, Chapter 19. 

  3. To some people, this statement sounds too much like trying to earn salvation by doing good works. They argue that there is only one use for the moral law of God, and that is to reveal God’s righteousness, give us knowledge of sin, and show us our need of pardon and our danger of damnation to Hell in order to lead us to repentance and faith to Christ—a usage that ended at the Christian’s conversion. But Lutheran and Reformed Christians have consistently argued that, as Christians, we should show our love for God by doing good works; and that this surely involves keeping God’s moral commandments, which are also Christ’s commandments to us (see Matthew 5-8; 22.36-40; 28.20; John 14.15 Ephesians 2.10). Lutheran and Reformed churches have traditionally taught that there are three uses of the moral law: (1.) conviction of sin in the non-Christian (as a “schoolmaster to bring us unto Christ” (Galatians 3.24), (2.) civil restraint of evil, and (3.) teaching Christians in the way of righteousness. E.g. see the Lutheran Formula of Concord, Article VI, and Calvin’s Institutes, Book 2 Chapter 7. In his Commentary of the Heidelberg Catechism, Zararias Ursinus has developed a different scheme based on the “fourfold state of man,” which is also very helpful. 

  4. See the Westminster Shorter Catechism, question and answer 14. 

  5. The Christian church has always understood that we can sin in thought, word or deed, and that sin can be by commission or omission

  6. Here I am drawing phrases from the Westminster Confession of Faith, chapter 19.