Proof texting has some value in certain situations, but if we want a comprehensive treatment of a doctrine throughout Scripture, it requires something more. If we limit the evidence on a doctrine to one book, one part of Scripture, or one writer, we will not have the whole story. The Red Letter Christians exemplify this, essentially saying that what Jesus said is more important than what one reads elsewhere in Scripture. Even if not overtly identifying as Red Letter Christians, others display this same thinking, particularly in dealing with the law.
It is common to focus on the Sermon on the Mount as the apex of Jesus’ teaching. Indeed, there is much ethical teaching here. But one also finds things that are situational, Jewish, and what belongs to the Old Covenant.
How do we deal with what Jesus said about the Mosaic Law? Are we bound to it, or not? Looking at the Sermon, one finds statements such as “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished.” (Matt. 5:17-18)
This seems decisive. Jesus is telling his hearers that he did not come to abolish, to tear down, but to fulfill. The law is permanent. He goes on to say “Therefore whoever relaxes one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever does them and teaches them will be called great in the kingdom of heaven. For I tell you, unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.” (5:19-20)
We are bound the keep the law, and our adherence to it is the measure of our righteousness. This seems to remove any doubt.
Or does it?
Looking only at the Sermon on the Mount will give us a truncated view of how the entire New Testament treats the law. One must consider not only what Matthew and the other evangelists record, but also what the apostles said. Some object to this as an invitation to confusion. R. Scott Jarrett, pastor of Denver Reformed Church observes this:
“We are to see the doctrine and theology established through the teachings of Christ as the standard which all the Christian writers of the New Testament are conforming to—and not the other way around. In other words, it is the principle of Christ before the other Christian teachers of the New Testament.”
This view is problematic, however. One can see how it is of a piece with the Red Letter view of inspiration and canonicity. But the Holy Spirit inspired Paul, as much as he did the four evangelists. This pits one part of the canon against another, suggesting that all of apostolic teaching should be read through the lens of what Jesus said—as if his words are the tie-breaker.
The distinction to the canon this introduces is unsustainable. It is the canon within the canon view; some books are more inspired than others. To adhere to this is to say that the Holy Spirit inspired the gospel writers differently or more so than he did than the writers of the New Testament epistles. This is to invite confusion in the interpretation of Scripture.
When we come to questions of the law and the Ten Commandments, one cannot arrive at a coherent position without the apostle Paul and all he wrote on the topic. There are ways to interpret Matthew light of Romans and Galatians, but choosing the Sermon on the Mount (or other parables) as the definitive way to treat the Mosaic law brings great difficulties.
To give one example, Paul writes in Romans 7:4, “Likewise, my brothers, you also have died to the law through the body of Christ, so that you may belong to another, to him who has been raised from the dead, in order that we may bear fruit for God.” A couple verses later we writes, “But now we are released from the law, having died to that which held us captive, so that we serve in the new way of the Spirit and not in the old way of the written code.”
One solution some have offered is to say that Paul is only speaking about the condemnation of the law that we are free from, but that the obligation still remains. C.E.B. Cranfield writes “The life promised for the man who is righteous by faith is, in the third place, described as a life characterized by freedom from the law, that is, from the law in the limited sense of the-law-as-condemning, or the law’s condemnation (cf. 8:1).”
But the law’s condemnation cannot be separated from commandment without the law ceasing to be law. Moreover, Paul assigns the law’s ability to kill to the commandment. “But sin, seizing an opportunity through the commandment, produced in me all kinds of covetousness. For apart from the law, sin lies dead. I was once alive apart from the law, but when the commandment came, sin came alive and I died.” (Rom 7:8-9) As Mark Seifrid notes, “When Paul speaks of ‘the law’ he has in view the commands given at Sinai, which cannot be detached from their authority to condemn without ceasing to be ‘law.’”
Those who affirm we are still bound to the Ten Commandments must contend with Paul’s clear statements of release from them. Some may say the reverse is true: Those who affirm freedom from obligation must deal with Jesus’ statements about not relaxing any of the commandments. The key is in seeing that fulfillment (which Jesus promised in himself) brings a changed relationship to the law. Obligation remained “until all is fulfilled.” But, that fulfillment has come in the person and work of Jesus.
Of all the ways one may answer questions about the Old Covenant law, we need gospel and epistle, Jesus and Paul. We need to consider everything the Holy Spirit has inspired.
 C. E. B. Cranfield, A Critical and Exegetical Commentary on the Epistle to the Romans. ICC 32a. 6th ed. (Edinburgh, UK: T. & T. Clark, 1975), 331.
 Mark A. Seifrid, Christ, Our Righteousness: Paul’s Theology of Justification. (Downers Grove: Apollos, 2000), 126.