1 John 2:4-5
“Whoever says “I know him” but does not keep his commandments is a liar, and the truth is not in him, 5 but whoever keeps his word, in him truly the love of God is perfected.” (1 John 2:4-5)
The apostles consistently appealed to the life and teaching of Jesus as having the highest authority. No wonder the apostles made this teaching the touchstone of truth. For example, Paul exhorts Timothy, “If anyone teaches otherwise and does not agree with the sound words of our Lord Jesus Christ . . . he is puffed up with conceit, he knows nothing” (1 Tim. 6:3-4). Then with apostolic authority they added teaching they themselves received from God. This was in the form of commandments — hundreds of them — and in descriptions and explanations of the way Christians should think and live. For example, the description of love in 1 Corinthians 13 or of the fruit of the Spirit in Galatians 5 presents a standard of thrilling grandeur for Christian behavior. Negative descriptions also abound, as in Paul’s description of the works of the flesh—fornication, uncleanness, lasciviousness, idolatry, sorcery, enmities, strife, jealousies, wraths, factions, divisions, parties, envyings, drunkenness, reveling, and such. Does he intend this as benevolent counsel or as law? He leaves no doubt: “I warn you . . . that those who do such things shall not inherit the kingdom of God!” (Gal. 5:19-21). Happily, all shades of theological opinion affirm that the teaching of the apostles in the Epistles is fully authoritative as a standard for Christian living.
But what about the law revealed in the Old Testament? Do the apostles join Jesus in affirming this law as authoritative for the era of the church? The apostolic answer, as in the case of Jesus Christ, seems to be a yes and a no (see 1 Corinthians 9:19-23). Are we under the law? Yes, say the apostles (Romans 13:8-10). Are we under the law? No, say the apostles, especially Paul (Romans 6:14).
The words the apostles use seem clear enough: “He who says, ‘I know him’ but disobeys his commandments is a liar, and the truth is not in him” (1 John 2:4-5). “So the law is holy, and the commandment is holy and just and good” (Rom. 7:12). “You are not under law but under grace” (Rom. 6:14). “But now we are discharged from the law” (Rom. 7:6).
How may these teachings be reconciled? Only a very small minority of Bible scholars have ever denied that the Old Testament law and the teachings of Christ prior to the upper room discourse (John 13–17 17) are addressed to Christians. Rather, the majority of theologians throughout church history have sought a resolution of this apparent conflict by making a clear distinction among the various uses of the term law and, on the basis of this, holding that the moral law is enduring, and the ceremonial law has been done away with. But this is not easy to do. Neither Moses nor the prophets made this distinction, and it is not always apparent what is moral and what is merely ceremonial. Furthermore, though Jesus seemed to distinguish the two by his behavior and what he stressed, neither did he make this distinction explicitly. But the gravest problem with this interpretation is that Paul himself did not seem to make this distinction. He seemed often to lump together everything in the Mosaic economy as “the law” and to teach that in Christ we have done away with it. In Paul there is no distinction between the Decalogue and the rest of the law. The law is one, the revealed will of God.
But what of “moral” law? In solving this dilemma of strategic importance, perhaps the common wisdom will lead us to the best solution. Throughout church history the Ten Commandments have been taken as the epitome of moral truth, a summary of what God expects of man. The Ten Commandments seem to summarize what the descendants of the Patriarchs already understood. Did they understand solely because the laws were imprinted in their moral consciousness, or were those laws communicated by God in other ways unknown to us?
Does the law produce “legalism?” The law is good (Romans 7:12), the law is spiritual (v. 14), the law is continuing in effect (Matthew 5:17-19), but it is only good if it is used lawfully, as it was intended (1 Timothy 1:8). How is it possible to misuse the law? How can the law be used illegally or unlawfully?
The Bible opposes legalism. It has ever been man’s method of attempted salvation. This is the primary meaning of legalism — relying on obedience to law for acceptance with God.
It is quite possible to teach salvation by grace through faith alone and yet to be legalistic, misusing the law by seeking to “save” oneself through obedience to the law. can be seen when a Christian measures his own acceptability with God or the acceptability of other Christians with himself on the basis of performance. Closely related to the motive of obedience for self-glory is obedience through one’s own strength. When we try to obey the law without relying on the enabling of the Holy Spirit, we, though saved by grace, are “saving” ourselves by works. Yet the highest motive is love. Obedience out of gratitude for all the gifts of grace is the best antidote to the virus of legalism.
 See Introduction to Biblical Ethics (IBE) for a fuller explanation.