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What does this say about your own conversion, if you refuse to study in order to obey the moral law as a Christian?

In the apostle Peter’s list of seven marks of grace that we must add to our faith (2 Peter 1.5-7), the second mark that we are commanded to add is knowledge.1

We must add knowledge to our virtue. We need to gain knowledge of God’s ways and character, of his requirements of us, and of the great doctrines of the faith. All this we do by studying the Holy Scriptures.

There is much that could be said about saving knowledge2 here, but I will focus on one important matter in knowledge that pertains to virtue.

It is astonishing how many how many churches these days teach that we do not need to study God’s moral law, or to retrain our own sin-damaged consciences by it, or to consciously obey it. When we affirm that this is what we really ought to do, even as Christians, they who look aghast at us and criticise us as though we are legalists.3

We respond to those who argue against us in this way: “You can’t really be saying that we should not keep the moral law of God. As a Christian, you can’t argue that we don’t have to live a moral life. So, what are you saying?”

Here they say, “Yes, of course, we should all try to live a moral life. But you shouldn’t try to save yourself by keeping God’s law. What you should be doing instead is believing in the Lord Jesus Christ for salvation. And you don’t need to study all this Old Testament stuff with a view to keeping it yourself. We are Christians now—we are in the New Covenant.”

So we respond again: “But we are Christians, not legalists. We are not trying to save ourselves by doing good works. Our motive now in learning God’s moral law is to learn how we should live as godly Christians.”

But then they say: “If you were Christians, then you would have the Holy Spirit teaching your conscience how you should live. You don’t have to study the Old Testament moral law for the purposes of doing that. Instead, you should ‘Walk in the Spirit, and ye shall not fulfil the lust of the flesh’ (Galatians 5.16).” And, they argue: “The purpose of the law was to lead the Jews to Christ, as a schoolmaster teaches his students—and if you have indeed become a Christian already, then you don’t need the schoolmaster any more (Galatians 3.24-25).”

And so we respond again: “Did you not read in the Gospel of John, in the New Testament, that when Christ prayed to his Father for us, he prayed, ‘Sanctify them through thy truth: thy word is truth’ (John 17.17)? And is not the moral law of God in the Old Testament an integral part this God’s word that Jesus was referring to? Of course it is! Therefore, instead of setting any portion of the Bible aside in this important matter of sanctification—i.e. of living a virtuous, God-glorifying life—you should study it and pray for the Holy Spirit to enable you to understand and to obey God’s moral laws.”

And we further point out that the Lord Jesus Christ, in his Sermon on the Mount (Matthew 5-7) and in other places, did not cancel the moral law. No, how foolish and how eternally damning it is to think that our Lord would teach that we shouldn’t keep the moral law of God! Rather than doing away with these laws Christ interpreted them in the most intense, most comprehensive way—applying them not only to our outward actions but to our innermost thoughts.

For example:

  • “Ye have heard that it was said by them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment: But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire” (Matthew 5.21-22).
  • “Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matthew 5.27-28).
  • “Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; That ye may be the children of your Father which is in heaven…” (Matthew 5.43-44).

We agree that the law is a schoolmaster through which the Jews and proselytes—and anyone else who reads it, even today—should be led to Christ (Galatians 3.19-24; 4.1-7; see also Luke 24.4; John 5.39). And we also agree that “The law of the LORD is perfect, converting the soul” (Psalms 19.7).

But you must read on in the nineteenth Psalm. Then you will see that studying the law makes the simple to be wise, and rejoices the heart, and enlightens the eyes; and that it is so precious that we should treasure it above a treasury full of the finest gold such as king David possessed, and that it is far sweeter to the spiritual tastes of godly people than anything in the world (vv.7-10). “Moreover,” David continues, by the laws of God is the servant of God “warned” about immoral life choices, and he is promised a “great reward” for living a righteous, virtuous life (v.11).

Seeing that all these things are true, what does this say about your own conversion, if you refuse to study in order to obey the moral law as a Christian?

We also know that “There is none righteous, no, not one” (Romans 3.10), and that therefore salvation can never be earned by fallen, totally depraved sinners of mankind. Salvation can never come “by works of righteousness which we have done,” but it comes by God’s “great mercy” (Titus 3.5; see also Romans 4.4-5).

The hearts of people who are not, or not yet, “born again” (see John 3.3-8) are sinfully set against God’s moral law. Basic moral principles are written on our consciences, but when it comes to loving God himself, and judging themselves by his moral laws, they want nothing to do with it. They are not merely disinclined to obey God—they are in open rebellion against God.

Whereas those people whose hearts have been changed by God will know the truths of the nineteenth Psalm in their own personal experience. And they will also pray and sing with the Psalmist in the hundred and nineteenth Psalm:

“O that my ways were directed to keep thy statutes…Open thou mine eyes, that I may behold wondrous things out of thy law…Give me understanding, and I shall keep thy law; yea, I shall observe it with my whole heart…Quicken me after thy lovingkindness; so shall I keep the testimony of thy mouth…O how love I thy law! it is my meditation all the day…I hate vain thoughts: but thy law do I love…Thy word is very pure: therefore thy servant loveth it…My soul hath kept thy testimonies; and I love them exceedingly” (Psalms 119.5, 18, 34, 88, 97, 113, 140, 167).

Christian, you need to add virtue to your faith—and in order to do that, you also need knowledge of God’s moral law in order to understand what virtue (moral excellence) is.


  1. The New Testament Greek word translated “knowledge” here is γνωσις (gnosis) (Strong’s Concordance, Greek Dictionary, #1108). 

  2. The phrase “saving knowledge” is famous in Reformed Christian circles, perhaps because it is the title of a very helpful book, The Sum of Saving Knowledge, by David Dixon and James Durham. 

  3. The true definition of a legalist is someone who hopes to earn salvation by Mosaic Law-keeping; or who elevates Law-keeping to an unscriptural importance, adding it to God’s grace in salvation.