Some Thoughts on the Unity of the Old and New Testaments
Last year a prominent nationally known pastor advocated that Christians needed to unhitch themselves from the Old Testament. This set off a firestorm of debate online. His motivation for calling for such action was due to his passion to reach the lost for Jesus Christ and he sees the Old Testament as a hindrance to this objective. He argued that what people need to know, without getting into all the messy details of the Old Testament, is simply that Jesus Christ rose from the dead. He backed this up with the teaching that the early church itself (the Counsel in Acts 15) distanced itself from the Old Testament. The writer of Hebrews declares that the Old Testament is obsolete (Hebrews 8:13). So it would be a good thing for Christians to simply unhitch themselves from the Old Testament. He did not deny the inspiration of the Old Testament but did call into question its value and its applicability for evangelism and Christian discipleship.
The idea of Christians unhitching themselves from the Old Testament is not new for it has been advocated before. A fellow named Marcion who lived in the first half of the second century AD due to his gnostic and dualistic beliefs rejected the God of the Old Testament as a wrathful deity while affirming that the loving and forgiving God of the New Testament to be the true God. He went further and rejected the Hebrew Scriptures and took his interpretive scissors and cut out everything from the New Testament documents that he saw as reflecting too much of the Old Testament. When his cutting job was over he was left with eleven documents in his canon, which consisted of sections from Luke’s Gospel and then of Paul’s letters. This paper is a humble attempt to show that such a stance toward the Old Testament is not justified for the simple reason that the two testaments are an organic unity.
However, even for those who do not share this view understanding the relationship of the Old Testament to the New Testament can be difficult. What is the nature of that relationship? In what way or ways are the Old and New Testaments unified? What about Old Testament laws? Are they still enforce today? These are important questions. This paper attempts to answer these questions and show how the Old Testament and New Testament are unified.
Christ fulfills the Old Testament
An important text that needs to be examined regarding the unity of the Bible is Matthew 5:17-20.
"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. 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. (Matt. 5:17-20 ESV)
What does Jesus mean when He declares with emphasis (emphasis which comes from the negative imperative, "Do not think), "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them"? The word abolish means to destroy but here it means something like "to end the effect or validity of something," thus to make something invalid or to annul a thing. Jesus teaches that He has not come into the world to annul or make invalid the Law or the Prophets. This is a reference to all the Hebrew Scriptures and not primarily or exclusively to the Law of Moses. This would also be the case in verse 18 where He references the Law. The Law is also used here as a title for the Hebrew Scriptures. Jesus is not just dealing here with the commandments of Mosaic law or only the commandments found in the Hebrew Scriptures but with the entire Hebrew Bible with its imperatival force or authority for God’s people.
This is brought out also in verse 18 where Jesus again affirms the valid duration of the written text of the Hebrew Scriptures. There are two “until” clauses. The first underscores that the duration of those Scriptures will last until heaven and earth pass away. When Jesus uses the terms “iota” and “dot” He is speaking about the written text of the Hebrew Scriptures. The iota is the smallest Hebrew letter yod י and a dot or tittle is any of the slightest difference in a few of the similar Hebrew letters like the het ח or he ה. He means that the written text with its content will not pass away or cease to be in force until the end of the present age.
The second until clause parallels Jesus' declaration in verse 17 when he states that he has come to fulfill the Hebrew Scriptures. The word accomplished as "until all is accomplished," can be translated "until all has come to pass." The word "all" has no antecedent and thus should be understood as referring to all the Scriptures and not merely to particular commandments. This second until clause affirms that nonetheless, all the Hebrew Scriptures must come to pass. They have a telic nature or by their very existence, a built-in prophetic design or purpose.
This is indeed what Jesus means when he states that He has come not to invalidate the Law or the Prophets but to fulfill them - all of them. The word fulfill has to do with how Jesus as the Messiah is the intended goal of the Hebrew Bible. They all point to the Messiah. Jesus of Nazareth is that Messiah and therein His coming and the carrying out of His Messianic mission fulfills the particular and overarching prophetic or promissory nature of the Hebrew canonical Scriptures. With His coming and the kingdom which He has established and will by His Second Advent consummate, He has fulfilled the Hebrew Scriptures by bringing them to their promissory goal.
Jesus puts Himself at the very center of how a person interacts with and handles the Hebrew Scriptures. In the larger context of what has been called the Sermon on the Mount, Jesus has gathered His disciples (those who have come to follow Him). Through Him, God is their Father and it is out of this reality that His followers come to understand the Scriptures and are enabled to obey them. They are the ones who are blessed because through Christ they have entered the Kingdom and bear the graces listed in the Beatitudes (Matt. 5:1-12). It is through Him and Him alone that they are put right with God and can call the Father of the Lord Jesus Christ their Father. They seek to do good works before men that those men might glorify their Father who is in heaven. He is the One whom Jesus teaches them to address in prayer as "our Father in Heaven." Jesus then brings out the true interpretation of the Hebrew Scriptures and in doing so shows that He has not invalidated them but has fulfilled them and His disciples are to see those Scriptures through the lens of their fulfillment in Him.
The nature of His fulfilling the Hebrew Scriptures without invalidating their authority for God's people is thus found in the fact that they are to be approached and interpreted through Him. One's rank in the Kingdom, (not one's entry) which He has established and will consummate, depends on how one handles the commandments of the Hebrew Scriptures. Those who relax "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" (vs 19).
In the rest of what is called the Sermon on the Mount, Jesus as the Messiah, who fulfills the Hebrew Scriptures, gives His authoritative interpretation of some of those commandments. In doing this He is not adding anything new to them but rather is fulfilling them by showing how they are to be interpreted. In doing this He is not contradicting Moses or the prophets but He is demolishing the system of scribal interpretations that for all practical purposes circumvented true godly obedience to those commandments. The scribes were seen as the authoritative interpreters of the Law and the Prophets. However, along with the Pharisees and their traditions, the scribes added to the Scriptures and this not only placed more minutia on people's shoulders but lessened the demands of the Scriptures too. The scribes were not merely legalists, who saw their compliance to those human traditions (which in their minds meant that they were obeying the Scriptures) as what put them right with God (Luke 18:10-14) but they were also antinomians. For their traditions allowed them in many situations to loosen the law and to find legal loopholes around having to do what the Scriptures commanded.
It is in light of this that Jesus teaches that "unless your righteousness exceeds that of the Scribes and Pharisees, you will never enter the kingdom of heaven." Rather than relax those commandments or to seek loopholes around them Jesus’ followers are through Him to seek to obey them. He is the key here. Apart from acknowledging Him as the one who has come to fulfill the Scriptures and thus that He is indeed the promised Messiah, one will not approach the Scriptures following the truth or give heed to them. This was what the Scribes and the Pharisees failed to see and thus they could never obtain true righteousness and hence they would not enter the kingdom of heaven. Those who look to Him as the One who fulfills the Scriptures will have a righteousness that exceeds the scribes and the Pharisees and will enter the kingdom of heaven.
Jesus’ teaching here also anticipates the New Testament
The Apostolic witness to Christ, which is the Gospel, was being proclaimed by the Apostles and their associates throughout the Roman Empire. Yet the early church looked to the Hebrew Scriptures as their authoritative canonical Bible. They used the Old Testament in their preaching in the very way we find Jesus using it with it when he met with them after His resurrection. Two texts in Luke show this pattern and it is most certainly followed in the various sermons recorded in Acts.
Luke records Jesus traveling (at this point incognito) with two of his disciples on the road to Emmaus. They are disturbed and upset not only due to the death of Jesus whom they believed was a prophet “mighty in deed and word before God and all the people,” but also due to reports from some of the women disciples that they did not find His body when they visited his tomb but angels who said he was alive. What is interesting is that Jesus does not reprimand them for failing to believe the women but for their failure to believe the Scriptures (Moses and all the Prophets).
And he said to them, "O foolish ones, and slow of heart to believe all that the prophets have spoken! Was it not necessary that the Christ should suffer these things and enter into his glory?" And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself. (Lk. 24:25-27 ESV)
He probably began with texts like Genesis 3:15; Deuteronomy 18:15: Psalms 2:7; 16:8-11; 110:1; 118 and Isaiah 53 to mention a few.
Later that evening he appeared to eleven of the Apostles huddled secretly in dismay and fear and verified that the one standing before them was the One they knew as Jesus of Nazareth who is the Christ now risen from the dead by showing them His wounds and eating some fish.
Then he said to them, "These are my words that I spoke to you while I was still with you, that everything written about me in the Law of Moses and the Prophets and the Psalms must be fulfilled." Then he opened their minds to understand the Scriptures, and said to them, "Thus it is written, that the Christ should suffer and on the third day rise from the dead, and that repentance for the forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem. You are witnesses of these things. (Lk. 24:44-48 ESV)
He teaches that everything that was written about Him in the Hebrew Scriptures (the Law of Moses, the Prophets, and the Psalms) had to be fulfilled. He summarized what those Scriptures taught must be fulfilled. Then He commissioned them: "You are witnesses of these things." It is the witness of the Apostles that comes to form the documents of the New Testament Scriptures. Their oral witness would not suffice after their death so a more permanent record of what they witnessed with their God-breathed interpretation was required.
So the unity of the Old and New Testaments is seen in the relationship between them in terms of promise and fulfillment. Every house as a foundation and a superstructure. They are different and perform different crucial functions but both are vital and necessary. Together they comprise one dwelling. The house of recorded salvation history begins with the promissory foundation of the Old Testament and it is completed by the fulfillment-superstructure of the New Testament.
Their unity comes from the dynamic of promise and fulfillment that has the Messiah as the link in both. He is the one promised not only in particular texts but in the broader patterns and themes of the Law, the Prophets, and the Writings, as well as in particular personages and offices and the system of worship of priesthood, sacrifice, and temple. The Christ or Messiah that was promised is Jesus of Nazareth. It was this man who claimed to be the promised Messiah who confirmed His claim by His deeds and words. By His incarnation, life and subsequent ministry following His baptism by John culminating in his death, resurrection, and ascension He fulfilled all that was promised. The NT documents are the God-breathed eyewitness records of the work Jesus of Nazareth accomplished and in doing so proved that He was the goal of all that the OT promised. This means that they cannot ever be separated. We cannot unhitch them. The only way we know how Christ fulfilled the Old Testament Scriptures is by reading and studying the New Testament documents. The Old Testament gives the necessary context for understanding the New Testament and the New Testament provides the interpretive light for understanding the Old Testament.
B. B. Warfield provided this helpful analogy of the relationship between the Old Testament and the New Testament. “The Old Testament may be likened to a chamber richly furnished but dimly lighted; the introduction of light brings into it nothing which was not in it before; but it brings out into clearer view much of what is in it but was only dimly or even not at all perceived before.” When he writes of “the introduction of light” he is referencing the coming of the Son of God in the flesh. The coming of Christ for the sake of the nations Paul calls “the mystery,” (Romans 16:25; Ephesians 3:3-9 and Colossians 1:26-27). The word “mystery” refers to that which is hidden and only known by God and can only be revealed by God. That mystery is Christ as he is revealed in the Old Testament Scripture but like a chamber richly furnished but dimly lighted." The hiddenness of Christ Warfield captures in his analogy of the furnishings in the room. They are there but are not as clearly seen until the light of Christ’s fulfillment occurs in salvation history.
Nevertheless, as that light dawns with the coming of Christ and the movement of the Gospel in the first century through the Apostolic witness it is the content of the prophetic writings now seen from the vantage of Christ that reveal that mystery to all the nations. Paul puts it this way: “Now to him who is able to strengthen you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery that was kept secret for long ages but has now been disclosed and through the prophetic writings has been made known to all nations,” Romans 16:25-26. So that mystery of the Gospel has now been disclosed and through the prophetic writings (the Old Testament Scriptures) been made known to all nations. The Old Testament Scriptures were used in spreading the Gospel through the Roman Empire of the first century. Those early Apostles and Christians did not unhitch themselves from the Old Testament but used it even in their evangelism. The mystery revealed in salvation history was inscripturated in the documents of the New Testament which provides us with a written authoritative witness to that mystery that has been revealed. So both Testaments must be held together if the Gospel is to be understood and effectively communicated and believed for salvation. There can be no unhitching of the New Testament from the Old. They now function as the authoritative canon for the church of the Lord Jesus Christ.
The Role of the Two Testaments or Covenants in the Unified Biblical Canon
Therefore, does this mean that there are no differences between the two testaments? Does this mean that everything found in the Old Testament is applicable for Christians? There are indeed differences or what we might call discontinuities but there are also continuities. It could be put like this: "Everything that is revealed in the Old Testament Scriptures is applicable for Christians as those things revealed are worked out in light of Christ's fulfillment of the Old Testament."
This brings up the importance of God relating to us through covenants. While the Old Testament Scriptures remain as an authority for Christians this is not the case with the Mosaic covenant or what is also called the Sinaitic covenant, the particulars of this covenant are found in the Pentateuch, especially in the books of Exodus, Leviticus, Numbers, and Deuteronomy.
Even before the Mosaic covenant, we find God relating to Adam and Eve through a covenant. They were created and given certain directives by God. These were stipulations or laws that included being fruitful and multiplying, tending the garden and exercising dominion over creation as vice-regents under the Creator. There was also the command of prohibition not to eat from the tree of the knowledge of good and evil. With that prohibition, there was a pronounced judgment of death and an implied blessing of life for obedience. This has been called the covenant of creation or the covenant of works. Eternal life for Adam and his posterity in this covenant was based on his obedience to these commands. Failure brought death as spiritual, physical and eternal. So Adam stood as the covenantal representative or federal head for all human beings. (Genesis 2:15-17 and Romans 5:12-18). While Adam broke covenant by sinning and thus brought both sin and death into the human race, God in His mercy promised a redeemer whom He called the Seed of the woman in Genesis 3:15. This brought into view the promise of a new covenant, a covenant of grace.
The covenant of grace comes into salvation history in earnest when God called Abraham. The covenant of grace is mediated through the Gospel. We find this when Abraham believed God's promise and was declared righteous (Genesis 15:6). Paul makes much of this in Romans and Galatians. The promise that God would give childless Abraham numerous descendants and through him all the nations would be blessed since from his numerous descendants One would come who would be his Seed, for Paul this was the Gospel. We might say that here was the oak of the Gospel in acorn form.
“Just as Abraham "believed God, and it was counted to him as righteousness"? Know then that it is those of faith who are the sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, "In you shall all the nations be blessed." So then, those who are of faith are blessed along with Abraham, the man of faith…Now the promises were made to Abraham and his offspring. It does not say, "And to offsprings," referring to many, but referring to one, "And to your offspring," who is Christ,” (Gal. 3:6-9,16).
God also made it plain to Abraham that his descendants would become slaves in Egypt and when the iniquities of the Amorites reached full measure He would deliver them from bondage and bring them into the land of Promise (Genesis 15:13-21). God fulfilled His promise to Abraham in the Exodus. By grace, He delivered His people from terrible bondage. He carried them out on eagle's wings and brought them to Himself (Exodus 19:4). It was by grace that He chose them and not due to anything in themselves (Deuteronomy 7:6-8). However, it seems clear that there were elements of the covenant of works operating within the Mosaic covenant too. This is at least Paul's emphasis in a number of his letters (Romans 4:15; 5:12-13; 6:12;7:1-6, 10; 10:5; Galatians 3:10; 5; 2 Corinthians 3:7-10). What are we to make of this?
The Abrahamic covenant was in place during the Exodus and throughout the history of Israel and added to it was what Paul calls the Law (the Mosaic law as a covenant of works). He speaks to this in Romans 5:12ff. In salvation history, the Law of Moses was added to expose the problem of human sinfulness. The moral law (particularly in the Ten Commandments which were applied in all the case laws to the people of Israel) was never given as the path one must tread to secure eternal life. The Law according to Paul in Romans chapter five was given not only to reveal sin but to exacerbate sin (Romans 7:5, 8). Human sinfulness or what Paul calls the flesh is unable to obey God's law. There is no way that human fallenness wants peace with God. (Romans 8:6-7). So Paul makes it very clear that the Mosaic Law brought to light the covenant of works. It demanded complete obedience to secure life and those who relied on their obedience to the law for acceptance with God would come under the curse of the law (Galatians 3:10-12). In part, this was done to expose the legalistic default setting of the heart. For our sinful nature not only covers over the depths of our sinful depravity but also leaves us with the outlook that by our works we can be put right with God. The law when applied by the Holy Spirit demolishes this myth and exposes the true ugly depths of our latent sinfulness and leaves us exposed and desperate.
Jesus Christ, by fulfilling the Old Testament, established what He called the New Covenant. This was promised in the Old Testament (Jeremiah 31:31-34; Ezekiel 36:25-27). He speaks of this when on the night he was betrayed and instituted the Lord’s Table declared concerning the cup: “this is the cup of the New Covenant in my blood” (Luke 22:20 and 1 Cor. 11:25). Now to be clear Christ was present in Gospel grace through types and shadows during the entire administration of the Mosaic Covenant. It isn’t simply that Moses is all Law and no grace and Christ is all grace and no law. Or to put it another way, it isn’t that the Mosaic Covenant is all Law and no grace and the New Covenant is all grace and no law.
So how was Christ present or how was grace operating in the Mosaic covenant? Well, in one sense it was a gracious gift that God gave His Law in written form. Certainly, the Law and its application in case laws including dietary laws and civil laws were to be obeyed by Israel. Yet, it was also clear that no one could keep those laws fully or perfectly. This fact should have humbled them and moved them to seek God's mercy. God's mercy and grace in Christ in shadow form were found in the cultus or what was the system of worship involving the Levitical priesthood, the sacrifices, and the tabernacle. Likewise, it wasn't enough simply in a mechanical manner to offer sacrifices. One had to do this with a broken and contrite heart. We see what true contrition, repentance, and trust looks like especially in the Psalms. So David makes it clear that the sacrifices that God desires are a broken and contrite heart. The Lord does not delight simply in sacrifice nor is He pleased with a burnt offering (Psalm 51:16). Nevertheless, David goes on to clarify that when there is true contrition then the animal sacrifices are right and whole burnt offerings do please the Lord (Psalm 51:19). This is captured in Psalm 4:5: "Offer right sacrifices and put your trust in Yahweh." Sacrifices needed to be offered by faith in the proffered grace and mercy of God revealed in the sacrifice and in the priest who offered it on behalf of the contrite sinner for the application of its benefit to be effectual. So both in the priest who offered the sacrifice and in the sacrifice, the shadow of the Redeemer was cast before the eyes of faith.
The writer of Hebrews speaks of the entire system of Old Covenant worship as being comprised of shadows or types of the heavenly things or the things to come (Hebrews 8:5; 9:23; 10:1). Paul is even more specific when in Colossians 2:16 he speaks of Old Covenant practices of circumcision, dietary requirements, the various feasts (with their required sacrifices) and a Sabbath as “a shadow of the things to come, but the substance belongs to Christ.” So when the New Covenant is inaugurated in Christ all these things have become obsolete.“In speaking of a new covenant, he makes the first one obsolete. And what is becoming obsolete and growing old is ready to vanish away” (Heb. 8:13 ESV). It is probably the case that Hebrews was written before the fall of Jerusalem and the destruction of the Temple when there was no longer a possibility for such sacrifices and worship to continue or the writer might have mentioned such matters at this point. So what has become obsolete is not the Old Testament as canonical authority for Christians but the Mosaic covenant with its system of worship and its civil and ceremonial laws.
Paul sees the Mosaic covenant and its administration as a kind of spiritual or moral kindergarten for God's people. In the schema of salvation history with the coming of Christ and the inauguration of the New Covenant, God's people have come of age and no longer need the kind of spiritual tutelage that the Mosaic covenant provided the saints under Moses (Gal. 3:23-26; 4:1-3). He states that when the Law of Moses was inaugurated it did not annul the covenant God made with Abraham (Gal. 3:17). For Paul the Gospel of justification by faith and the promise of an inheritance that it secured remained in effect throughout the Mosaic economy. Even during this era of salvation history justification was by faith. It was not by relying on doing the law that one was justified and received the hope of eternal life (the promised inheritance).“For the righteous shall live by faith” (Gal. 3:11). Those who relied on their obedience to the Law came under judgment because no one could keep the Law for no one could do so with perfect obedience. “For all who rely on works of the law are under a curse; for it is written, "Cursed be everyone who does not abide by all things written in the Book of the Law, and do them” (Gal 3:10).
Those who came to faith during the Mosaic economy were God's underage children; those who, like David, understood that contrition over sin and offering sacrifices were both necessary They also came to see through the shadows and types that to pay for their transgressions meant death but it was indeed mercy that God allowed an animal to be offered in substitution. So in this sense, the Law served as a guardian (paidagogos) until Christ came (Galatians 3:24) Paul is using the analogy of a Roman slave who would be charged with the task of making sure the underage son(s) of the paterfamilias (the father and head of the household) made it to their lessons. The Law put strictures upon God’s Old Covenant people and the particulars of those civil and ceremonial laws were holy and were to be followed in the same way that preschool or kindergarten children need the structure and lessons of the classroom.
In fact, in Roman society, though an underage son was an heir until he came of age, he was treated like a slave. All those under the Old Covenant who were indeed believers were nonetheless subjected to laws and regulations that Paul called "elementary principles." Paul put it this way:
I mean that the heir, as long as he is a child, is no different from a slave, though he is the owner of everything, but he is under guardians and managers until the date set by his father. In the same way, we also, when we were children, were enslaved to the elementary principles of the world. But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of his Son into our hearts, crying, "Abba! Father!" So you are no longer a slave, but a son, and if a son, then an heir through God. Galatians 4:1-7
There is probably at least a couple of important theological realities that Paul intends to communicate here. What is important to note is that by His incarnation and birth Christ was born under the law. He took upon himself the obligations of the Mosaic covenant and hence the covenant of works that God had also set with Adam. In Romans 5:15-21 Paul writes of the contrast between Adam's disobedience that brought the reign of sin and death and Christ's obedience that brought righteousness that leads to justification and life. In Galatians 3:13 we read that “Christ redeemed us from the curse of the Law by taking upon himself that curse as he was crucified.” Christ redeemed those who were under the law as a covenant of works. In other words by His life of perfect obedience to the moral law of God and indeed to the entire Mosaic Law and by offering His life in bearing the curse of the law due to human sin and disobedience he redeemed us from the Law's condemnation. Yet, he did more for in Christ we who trust Him have come of age and God confirms that by sending the Spirit of His Son into our hearts who cries "Abba! Father! Christians are sons come of age and hence heirs. This means that we no longer need the “paidagogos” of the Mosaic covenant. That covenant has been annulled by Christ's coming and fulfilling its Laws and bearing its curses and thus securing its blessings of eternal life. It was by his obedience that the Mosaic Covenant has now become obsolete. In doing all this Christ has established the New Covenant.
Covenant discontinuities and continuities
Though we read of the necessity for animal sacrifice in the Book of Leviticus this is not binding on believers who are now under the New Covenant (Hebrews 10:12). Yet the Book of Leviticus gives us authoritative context and content to understand why Christ's sacrifice was so important and so effectual. Without the teaching of Leviticus, we would be the poorer when it comes to appreciating what Christ accomplished. This is also true of Exodus, Numbers, and Deuteronomy.
So, there is clear teaching from the New Testament that certain facets of the Mosaic Covenant have been discontinued under the New Covenant. This is most certainly the case with circumcision as the sign of the covenant being replaced by baptism (Col. 2:11-13) and the Passover meal being realized in Christ’s sacrifice which is signified in the Lord’s Table. Jesus Christ himself removed the necessity of all the Mosaic dietary laws and restrictions when He declared all foods clean (Mark 7:19). This does not mean that there is no value or benefit in studying Mosaic case laws for principles that can be applied under the New Covenant. Paul does this when he applies the case law from Deuteronomy 25:4 that forbade a farmer from muzzling an ox that was used for treading grain as giving instruction concerning the necessity of those called to Gospel ministry to be able to make their living from that ministry (1 Corinthians 9:9-11 and 1 Timothy 5:18).
There are indeed discontinuities between the two covenants yet even in this regard those discontinuities are due to Christ fulfilling the copies and shadows that pointed to Him. We are no longer required to worship God at the Temple because Christ is the greater Temple (John 2:1-22), so we go to God through Him and we meet with God in Christ. The Levitical priesthood is no longer needed because we have a greater Priest, Advocate and sufficient sacrifice all in Christ. So it isn’t that that sacrifices, temple, priesthood and covenant rites have passed away but rather they have all been fulfilled or have all reached their goal in Christ. The reality has replaced the shadow and copy and we indeed must avail ourselves of the reality of these heavenly things.
However, there are still some continuities. These have to do with the moral law as it was codified in the Mosaic covenant. When Paul writes in Romans 6:14: "For sin will have no dominion over you since you are not under law but under grace," it can be a bit confusing. In what sense are Christians no longer under the law? In Romans 13:8-10, Paul writes that believers are to owe no one anything (what he means is that we are to pay our bills), except to love each other. The Gospel binds us under its grace to love one another. Then he writes: “the one who loves has fulfilled the law.” Then he lists four of the commandments from the Decalogue: “‘You shall not commit adultery, you shall not murder, you shall not steal, you shall not covet,’ and any other commandment (from the Decalogue) is summed up in this word: ‘You shall love your neighbor as yourself.’” Then he makes this statement about the relationship between Gospel love and fulfilling the law: “Love does no wrong to a neighbor; therefore love is the fulfilling of the law.” So in this regard, the Law still has a place in the New Covenant economy (See also 1 Corinthians 9:21).
So at least in two ways, believers are no longer under law. Believers are no longer under the law as a covenant of works. One does not need to obey the law to secure acceptance a favor with God. Thus Christ as our second Adam has fulfilled the moral law in our stead and by faith in Him, we have been fully pardoned and justified. Believers are no longer under the Mosaic law with all its elementary regulations. We have by grace graduated, as it were, from spiritual childhood to in Christ coming of age. The heart of stone has been taken away and we have been given a heart of flesh upon which God has written His law and has poured out the Spirit of His Son into our hearts so that we are led by the Spirit to love our Father. Nevertheless, we remain under the Law (at least nine of the ten for there is some question about whether Sunday is the Christian Sabbath or the Lord's Day and that is another paper) as a rule of life. The Law helps us to see and to be clear on what genuine love that conforms to Gospel grace looks like in practice.
So the Bible of both the Old and New Testaments has authority over our lives as believers in Christ. In that, the Bible is intended by God to regulate our faith and lives as God's people. We have no right to unhitch the Old Testament from the New. As stated above the Old Testament provides the context for the New Testament. The New Testament authors quote from every Old Testament book except Esther and Obadiah, with 250 direct quotes but with indirect or partial quotes the number increases to well over 1,000. We might say that the New Testament is saturated with the Old Testament. This is especially the case with the book of Revelation that constantly alludes to the Old Testament. The New Testament authors were people of the Old Testament through and through. There are indeed discontinuities between the Old Covenant and the New Covenant but there are also clear continuities too. When it comes to the Scriptures being God's progressive revelation (Hebrews 1:1-3) the two testaments are not like a car being pulled by a trailer that is designed to be unhitched of but rather like a fine piece of furniture with exquisite dovetail joinery with distinct parts crafted together into a unified whole. Jesus made that clear - "Do not think that I have come to do away with the Law and the Prophets. I have not come to do away with them but to fulfill them." So He has!