Knowing Jesus Means Knowing the Old Testament—and Rejecting ‘Functional Marcionism’

This essay addresses the false dichotomy in the church of “Old Testament vs. New Testament” and the resulting forms of Marcionism.

The young man fumbled a bit as he reached for the chair and pulled it out for his date. He was clearly nervous. The waiter lit the candles as the youthful suitor took the seat across from her. Settling into his chair, the fellow told his date how excited he was to have dinner together, and she blushed. Then they began to talk. But here is the strange feature in this little parable with which my essay begins.

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That night, the fellow asked many questions about the young woman’s work and her hobbies, but he showed no interest in her family or her childhood. In fact, any time she mentioned her parents, he quickly changed the subject. He said he was interested in her for who she is today. He was not concerned to know her background.

How would you advise this young woman? I would tell her to lose the guy, and I suspect you would too.

If the fellow is not interested in his date’s history or her family, then he is not really interested in her as a person. He is not interested in all the Lord has done to make her who she is today. Relationships are built as lives are shared, and that includes family and history.

Somehow, many Christians overlook this principle in their relationship with Jesus. Many Christians suppose that the New Testament—which recounts the life of Jesus and the teachings of those who lived with him—is enough to build a relationship with him. Old Testament background and Jewish “family history” might be great for Jews, and maybe for Bible scholars. But, it is thought, the New Testament is all we need to know Jesus. That is false.

Jesus himself emphasized the importance of the Old Testament for knowing him (Luke 24:27). But sadly, Old Testament neglect has been common among Christians.

‘Functional Marcionism’ and the Early History of Old Testament Neglect

Old Testament neglect in the church can usually be traced to misunderstandings of Paul. The Apostle Paul gave firm instructions to the church not to continue the rituals of the Old Testament Law. He would not allow churches to require Old Testament rites such as circumcision or the dietary laws. He even “opposed [Peter] to his face” when Peter sent mixed signals on the matter. Paul proclaimed, “A person is not justified by works of the law but through faith in Jesus Christ” (Galatians 2:11–16). Unfortunately, these instructions have sometimes been misinterpreted.

In particular, one of Paul’s early readers misunderstood this angst over the works of the law. He thought Paul had renounced the Old Testament altogether! This man’s name was Marcion (85–160 A.D.). He lived a generation after Paul and never met the Apostle in person. But in his zeal for Paul’s epistles, Marcion rejected the Old Testament. By trade, Marcion was a shipowner at the Black Sea port Sinope. But he is remembered to history for developing a canon that lacked the Old Testament.

Today, few who call themselves Christians would outright deny the Old Testament as Marcion did. Paul himself wrote that “all Scripture is breathed out by God and profitable” (2 Timothy 3:16). And with close to a thousand citations of the Old Testament in the New, it is hard to justify Marcion’s disparagement. But even though we retain all 39 Hebrew books of the Bible along with the 27 in Greek, many Christians today approach the Bible as “functional Marcionites”—Christians who esteem the New Testament but consciously or subconsciously think less of the Old Testament, resulting in its neglect.

The Importance of the Old Testament for New Testament Faith

When Christians misunderstand the relationship between the Testaments, they tend to read the New Testament for their theology and turn to the Old primarily for illustrations and morality lessons. Neglecting or minimizing the Old Testament in this way can be a form of Marcionism. If we turn to Romans to learn about atonement and neglect careful study of Leviticus as well; if we read the lives of Abraham, Isaac, and Jacob to show that polygamy causes problems, but pay little attention to the covenants God established with them; and if we read the Psalms as Jewish hymns we admire, but not as Christian hymns we confess: we are at risk of Marcionism.

A loss of Old Testament engagement creates deeper problems than a mere lack of knowledge. Functional Marcionism breeds many dangers. For example, “Christian” anti-Semitism has often been fueled by a devaluation of the Old Testament and neglect of the church’s Hebrew ancestry. American “Evangelical” politics frequently cherry picks Old Testament verses to support certain political goals (e.g., policies on homosexuality), while remaining ignorant of major Old Testament themes (e.g., the calling upon God’s people to show hospitality to foreigners or other outsiders).

To neglect the Old Testament is, in fact, to neglect the New Testament.

Furthermore, a loss of Old Testament literacy actually deprives Christians of New Testament understanding! Like watching only the final movie from a series, a person who only learns the New Testament will miss all the allusions, references, and meaning the Apostles expect their readers to recognize based on Old Testament understanding. To neglect the Old Testament is, in fact, to neglect the New Testament.

Rejecting Functional Marcionism and Recovering Whole-Bible Faith

The relationship between the Testaments is often mischaracterized as replacement or obsolescence. It is true that the Old Testament Temple and its rituals have been discontinued. The old practices as practices are now “obsolete” (Hebrews 8:13). But the cross of Jesus did not repeal the Old Testament faith. The cross fulfilled—and thereby upheld—the Old Testament faith (Matthew 5:17–18). And the church still needs the Old Testament to know Christ and his kingdom fully.

For example, the book of Hebrews states, “Since the law has but a shadow of the good things to come instead of the true form of these realities, it can never, by the same sacrifices that are continually offered every year, make perfect those who draw near. . . . For it is impossible for the blood of bulls and goats to take away sins. Consequently, when Christ came into the world, he said, ‘Behold, I have come to do your will, O God, as it is written of me in the scroll of the book’” (Heb. 10:1–7).

The Old Testament sacrifices were never meant to accomplish atonement. Animal sacrifices were a means for ancient believers to participate vicariously in the true sacrifice yet to come. Everything written about sacrifices “in the scroll of the book” was written about Jesus, the real sacrifice.

What does this mean regarding the value of the Old Testament? It means that “the scroll of the book” is exceedingly valuable for our study of the cross. The Old Testament contains the detailed theology of what Jesus came to do. In fact, Jesus was thinking about the instructions in “the scroll of the book” as he went to the cross. The Old Testament was his guidebook. If we want to know the thoughts and heart of Jesus, we will study those writings that filled his mind and soul.

For instance, the book of Leviticus describes five different offering categories: burnt offerings (Lev. 1:1–17), grain offerings (2:1–16), peace offerings (3:1–17), sin offerings (4:1–5:13), and guilt offerings (5:14–6:7). Leviticus also describes the feasting before God that those offerings make possible (6:8–7:33). Thus, in the opening seven chapters of Leviticus, we learn how atonement resolves the complex and multifaceted layers of human separation from God, restoring communion in his house. The detail is contained in Leviticus. So when we consider the once-for-all sacrifice of Jesus and desire to delve into its significance, it is important to include Leviticus in that study.

Atonement is not the only doctrine that requires the Old Testament to be studied alongside the New. Our understanding of worship, the believing community, righteousness, the family, grace, humanity, sin, vocation, and all other themes of Christian faith require “the whole counsel of God” (Act 20:27). If we neglect the Old Testament, or limit its use to morality stories, we fall into an error similar to that of ancient Marcion.

The Abiding Necessity of the OT

A helpful way to think about the relationship between the Testaments is to imagine a builder who is creating something new. First, the builder draws up blueprints for his project. Second, he makes a prototype, a small scale model or “proof of concept” of his design. Then, with the blueprints ready and the prototype complete (with all the lessons learned in the course of developing the prototype), full construction begins.

In this word picture, the blueprints are the first five books of the Bible: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. The Hebrew name for that set of books is “Torah,” which means “Law.” Those five books are called “Law” because they form the “Kingdom Constitution” for God’s people. Its stories and commandments cast a vision for the kind of society God will build through his redeeming grace: a community marked by love for God and love for one’s neighbor (Matt. 22:34–40).

The whole world needs that grace, but God purposed to begin His kingdom with a prototype. In the early chapters of Genesis, God called a certain man (Abram) to a certain land (Canaan). And God promised to make a model kingdom from Abram’s household in that place, so that “in you all the families of the earth shall be blessed” (Gen. 12:3). The rest of the Old Testament describes that “proof of concept” project, as God built his model kingdom in Israel.

If we want to know the thoughts and heart of Jesus, we will study those writings that filled his mind and soul.

The New Testament introduces the final element in the building project. The blueprints (the Torah) are in hand. The “proof of concept” model (Old Testament Israel) was completed. The witness of that model, with all the lessons learned through its construction, is preserved in the books of the Old Testament. With these elements in place, the New Testament launches heaven’s full-scale kingdom project for the whole world.

When Jesus came, he announced, “The time is fulfilled, and the kingdom of God is at hand; repent and believe the gospel” (Mark 1:15). Jesus did not come to start something novel. He came to complete what was promised from of old: the good news of the Kingdom of God! Ignoring the Old Testament would be like throwing away the blueprints and the prototype just when we can most benefit from them, as we join the final project now under way. New Testament Christians need the Old Testament to foster a full and robust faith in Christ and his kingdom.

Sadly, the second century teacher Marcion taught otherwise. Marcion believed that the god of the Old Testament was cruel, and that he was a different being than the God of Jesus. Misreading Paul’s opposition to the works of the law, Marcion gathered disciples to himself and preached his “New Testament–only” style of faith.

In an effort to spread his ideas, Marcion sailed his ship to Rome. He delivered a generous offering of 200,000 sesterces to the church leaders there, and sought their support for his message. The ministers were troubled by Marcion’s errors and sought to correct him, but he refused their exhortations. They returned Marcion’s 200,000 sesterces and publicly warned the church against his teachings. We should continue to heed that warning, today.

The Apostles themselves had depended upon the Old Testament Scriptures, quoting from them extensively in their New Testament writings. The early church defended the importance of the Old Testament in opposition to false teachers like Marcion. Today, if we would know Christ and the fullness of the kingdom he is building, we too will hold fast to the essential unity of the Old and New Testaments.

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