The Relevance of the Old Testament

Understanding the relationship between the two testaments of the Bible is essential, yet the relevance of the Old Testament can be difficult to grasp, especially when distinctions are drawn between it and the New Testament. Many have come to neglect the Old Testament, dismissing it as stories for Sunday School or as purely obsolete. This is a mistake. It produces a faith disconnected from its foundation, unable to grasp the scope of God’s redemptive plan. Without the Old Testament, the New Testament is an arbitrary series of events. The Old Testament establishes the prophetic expectations that the New Testament fulfils. It introduces God’s covenants, His law, and the entire sacrificial system, which gives meaning to Christ’s work. The identity of Jesus as the Messiah is incomprehensible apart from the prophecies and royal lineage detailed in the Old Testament. The meaning of His sacrifice (Heb. 9-10) loses its context without the background of Leviticus and the Day of Atonement. The nature of the New Covenant (Jer. 31:31-34) is understood only in contrast to the Mosaic Covenant it perfects. The Old Testament provides the narrative baseline, revealing the origin of sin, the problem of human rebellion, and God’s consistent faithfulness despite that rebellion. As the Apostle Paul writes, the events of the Old Testament were recorded “as an example, and they were written for our instruction” (1 Cor. 10:11). Its narratives, laws, and prophecies are not obsolete. They are the foundation of God’s revelation, establishing His character, His holiness, and His redemptive purpose. While the application of certain laws has changed now that Christ has come, it is a fulfilment, not an abolition.

The Scriptures of Jesus and the Apostles

The Old Testament was the only Bible of Jesus and of the Apostles, even decades after the crucifixion, resurrection, and ascension of Christ. The New Testament was not written for some years after Christ’s resurrection but was developed through the witness of the early Church, inspired by the same Spirit. When Jesus, the Apostles, or the writers of the New Testament referred to “the Scriptures” (e.g., Matt. 21:42; Jn 5:39; Rom. 1:2), they were referring to the Old Testament. This collection of writings was the source of their theology through which they understood Christ’s life, death, and resurrection. This is why, after His resurrection, Jesus rebuked His disciples for their failure to understand what was already written. He met them on the road to Emmaus and described them as being “slow of heart to believe in all that the prophets have spoken” (Lk 24:25). Their failure was not recognising what the Son of Man would have to endure.

‘“Was it not necessary for the Christ to suffer these things and to enter into His glory?” Then beginning with Moses and with all the prophets, He explained to them the things concerning Himself in all the Scriptures.’ (Lk 24:26-27)

Later, He “opened their minds to understand the Scriptures” (Lk 24:45), showing that His death and resurrection were the prophetic fulfilment of the entire Old Testament story.

The New Testament writers followed this same pattern. They did not see what they wrote as replacing the Old Testament; they saw it as its ultimate fulfilment. Peter’s first sermon on the day of Pentecost was built on prophecies from Joel and the Psalms (Acts 2:16-36), arguing that the events they were witnessing were the fulfilment of Old Testament promises. Philip explained the gospel to the Ethiopian eunuch from a passage in Isaiah (Acts 8:30-35), showing how the suffering servant of Isaiah 53 was Jesus. The Gospel of Matthew is focused on demonstrating how Jesus’s life fulfilled specific Old Testament prophecies (e.g., Matt. 1:22-23; 2:15, 17).

The Apostle Paul’s core arguments depend entirely on the Old Testament. In his letter to the Romans, he uses Abraham as the primary example of justification by faith apart from works (Rom. 4). In Galatians, he builds his case for freedom from the law by referencing the Abrahamic covenant (Gal. 3:15-29). The book of Hebrews is an extended explanation of how Christ is the fulfilment of the Old Testament priesthood and sacrificial system, demonstrating that the old system was a shadow of the reality found in Christ (Heb. 8:5; 10:1). The New Testament provides a fuller picture of what was already present in the Old. Its core concepts, the covenants, sacrifices, priesthood, kingdom, and Messiah, are all defined by the Old Testament, which gives them their substance and meaning.

A Pattern of Salvation and Warning

The Old Testament also provides warnings about how God deals with a rebellious people. Throughout his letter to the Corinthians, Paul refers to the wilderness wanderings of Israel as a parallel for the Christian life. This typology carries significant meaning for Christians. Egypt, the land of bondage, is a type of the world system ruled by sin (Eph. 2:1-3). Pharaoh represents the spiritual forces that hold humanity captive. The Israelites came out of Egypt through the blood of the Passover lamb, a clear picture of redemption through Christ (1 Cor. 5:7). They were then “baptised into Moses in the cloud and in the sea” (1 Cor. 10:2) as they passed through the waters that cut them off from their old life and destroyed their enemies. This was a definitive act of separation from their past, just as Christian baptism signifies a believer’s death to sin and new life in Christ (Rom. 6:3-4). In the wilderness, they were sustained by manna from heaven (spiritual food) and water from a rock (spiritual drink). Paul states that “they were drinking from a spiritual rock which followed them; and the rock was Christ” (1 Cor. 10:3-4). Their journey was toward the promised land, a type of our future inheritance and the spiritual rest we enter by faith (Heb. 4:1-10).

In the same way, believers come out of the world through Christ, the true Passover Lamb, are baptised into Him, and journey through the wilderness of this life. We are sustained by Him as our spiritual food and drink, and we await entry into the ultimate promised land. Paul also uses the Passover imagery to instruct the church at Corinth on the issue of sin. Leaven is a symbol of sin because it puffs up (representing pride) and spreads corruption throughout a lump of dough (1 Cor. 5:6). Just as the Jews were required to diligently remove all leaven from their homes before Passover, believers are called to repent and remove sin from their lives. The command is urgent because Christ has already been sacrificed.

‘Clean out the old leaven so that you may be a new lump, just as you are in fact unleavened. For Christ our Passover also has been sacrificed. Therefore let us celebrate the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.’ (1 Cor. 5:7-8, NASB 1995)

Our position in Christ is that we are “unleavened.” Our practice, therefore, is expected to align with that position. This preparation for Passover is a picture of the repentance central to the gospel message: “Repent, for the kingdom of God is at hand” (Matt. 3:2, 4:17). It is the constant, ongoing and repetitive pattern of turning from sin to embrace Christ, not as a one-time act, but as an ongoing posture of the heart.

Heeding the Warnings of the Past

Paul applies the lessons from the wilderness directly to the Corinthian church, addressing the sins of immorality and idolatry by referencing the incident of the golden calf in Exodus 32. He reminds them that although Israel experienced God’s provision, their disobedience brought severe consequences. After receiving the Law from God, Moses returned to find the people engaging in idolatrous worship and revelry. Paul’s warning draws a parallel, comparing their failure to the temptations facing the Corinthians. He lists a series of Israel’s failures as examples for the church.

‘Now these things happened as examples for us, so that we would not crave evil things as they also craved. Do not be idolaters, as some of them were… Nor let us act immorally, as some of them did, and twenty-three thousand fell in one day… Nor let us try the Lord, as some of them did, and were destroyed by the serpents. Nor grumble, as some of them did, and were destroyed by the destroyer. Now these things happened to them as an example, and they were written for our instruction, upon whom the ends of the ages have come.’ (1 Cor. 10:6-11, NASB 1995)

These were not isolated incidents but patterns demonstrating a deeper issue. Their idolatry with the golden calf (Ex. 32) showed an impatience for a visible god. Their immorality at Peor (Num. 25) involved pagan worship through sexual temptation. They tried the Lord when they grumbled for water at Meribah (Num. 20) and complained about manna (Num. 21). Their grumbling against leadership was a constant theme (Num. 16). All these acts of rebellion reached their climax at Kadesh Barnea (Num. 13-14). After twelve spies were sent into the promised land, ten returned with a report of fear, focusing on the strength of the inhabitants rather than on the power of God. The people responded not with faith, but with terror and subsequent rebellion, weeping and demanding to return to Egypt. This was the defining moment of unbelief for that generation.

The writer to the Hebrews looks at this same history and identifies the root cause of unbelief. While Paul lists the outward sins as cautionary examples, Hebrews outlines the inward condition of the heart that produced them. The rebellion at Kadesh Barnea is the primary example used to warn against a similar failure. The writer frames his argument around Psalm 95, where God recalls Israel’s testing in the wilderness and swears an oath that they would not enter His rest. For the author of Hebrews, this “rest” was not just the land of Canaan, but a type of the ultimate spiritual rest found in Christ. The generation that fell in the wilderness had the “good news” of the promised land preached to them, but it was of no value because they did not combine it with faith (Heb. 4:2). Their failure was not a lack of evidence—they had seen God’s works for forty years—but a wilful hardening of their hearts against His promise.

‘“Today if you hear His voice, do not harden your hearts as in the rebellion, in the day of trial in the wilderness, where your fathers tried Me by testing Me, and saw my works for forty years… Take care, brethren, that there not be in any one of you an evil, unbelieving heart that falls away from the living God.”’ (Heb. 3:7-9, 12, NASB 1995)

The generation that came out of Egypt saw God’s works, yet they did not enter His rest “because of unbelief” (Heb. 3:19). Their grumbling, idolatry, and immorality were the fruit of a heart that refused to trust God’s promises. The warning for believers is therefore twofold. From Paul, we learn to flee from these specific sins. From the writer to the Hebrews, we learn to guard our hearts against the unbelief that gives birth to those sins. Spiritual privilege does not remove personal responsibility.

The Cycle of Sin in the Promised Land

The pattern of rebellion did not end when Israel crossed the Jordan. It continued in a relentless cycle, first under the judges and then under the kings, demonstrating with increasing clarity the depth of human sin and the necessity of divine intervention.

The period of the Judges was a chaotic time defined by a repeating pattern of apostasy and deliverance. The book of Judges summarises this tragic cycle: Israel would forget the Lord and turn to worship the idols of the Canaanites they failed to drive out. In response, God would hand them over to an oppressor as judgment for their sin. After a period of suffering, the people would cry out to the Lord for mercy. God, in His faithfulness, would then raise up a judge to deliver them. Following the victory, there would be a season of peace, but once the judge died, the people would return to idolatry, often sinking deeper into sin than the previous generation (Judges 2:11-19). This cycle of sin, servitude, supplication, and salvation repeats with figures like Othniel, Ehud, Deborah, Gideon, and Samson, but the story is a downward spiral. It culminates in moral anarchy and civil war, climaxing with the statement, “In those days there was no king in Israel; everyone did what was right in his own eyes” (Judges 21:25). The lesson for the church is a warning against spiritual compromise. Compromising with the world and adopting its values inevitably leads to spiritual corruption and forgetting the saving works of God.

The establishment of the monarchy was itself a product of this unbelief. The people demanded a king so they could be like other nations, effectively rejecting God as their true King (1 Sam. 8:7). While God granted their request, the history of the kings is largely a continuation of the same rebellion on a national scale. For every righteous king like David, Hezekiah, or Josiah who led the people in revival, there were many more wicked kings who led the nation into deeper and more institutionalised idolatry. After Solomon’s reign, the kingdom split in two. The northern kingdom of Israel was universally apostate, never having a single righteous king, until it was finally destroyed by Assyria. The southern kingdom of Judah had moments of reform, but it too ultimately fell into the same pattern, ignoring the constant warnings of prophets like Isaiah and Jeremiah. This history teaches that even the best human leadership and religious structures are insufficient to change a sinful heart. It warns the church against placing its ultimate trust in leaders, systems, or institutions rather than in God Himself.

The culmination of this centuries-long rebellion was the Babylonian exile, the judgment that God, through Moses, had warned of from the very beginning (Deut. 28). Yet even this exile did not produce lasting repentance. After the return from Babylon, leaders like Ezra and Nehemiah called the people to renew their covenant with God, and there was a brief period of restoration. However, the last of the Old Testament prophets, Malachi, confronts a people whose hearts had once again grown cold. They were offering unclean sacrifices, neglecting justice, and questioning the righteousness of God. The return from exile did not cure their rebellion. This entire historical record serves as evidence of the condition of the human heart. It dismantles every utopian “if only” scenario. Humanity could be given everything it believed it required for a healthy and happy life, including perfect laws, a land flowing with milk and honey, even the manifest presence of God, and it would still, left to its own devices, plunge itself into chaos. This centuries-long pattern unfolded through multiple forms of governance, from direct leadership under God, to judges, to human kings, all demonstrating that no external system can fix an internal problem. The root problem was not a lack of information, laws, or leaders, but a deep-seated inclination toward sin that no human system could fix. Only a divine reconciliation could establish a lasting peace. This history, therefore, makes the gospel not just good news, but necessary news, revealing our desperate need for the new heart and new covenant that only Christ can provide.

A Greater Responsibility

A common mistake is to assume God’s severity is lessened under the New Covenant because it is a covenant of grace. The opposite is true. Because believers have received the full revelation of Christ and His Spirit, the responsibility is greater. If disobedience to a lesser revelation brought judgment, then disobedience to a greater revelation will bring a greater judgment. The writer to the Hebrews makes this clear, contrasting the consequences of rejecting the Law of Moses with the consequences of rejecting Christ. Under the Old Covenant, revelation was mediated through prophets, priests, and sacrificial shadows. Under the New Covenant, we have direct access to God through the Son and the indwelling of the Holy Spirit.

‘Anyone who has set aside the Law of Moses dies without mercy on the testimony of two or three witnesses. How much severer punishment do you think he will deserve who has trampled under foot the Son of God, and has regarded as unclean the blood of the covenant by which he was sanctified, and has insulted the Spirit of grace? … It is a terrifying thing to fall into the hands of the living God.’ (Heb. 10:28-29, 31)

The language here is strong to show the seriousness of apostasy. To “trample under foot the Son of God” suggests treating Jesus with contempt. To regard the “blood of the covenant” as unclean is to profane the very means of our purification and redemption, dismissing His sacrifice as meaningless. To “insult the Spirit of grace” is to wilfully reject His conviction and the mercy He offers. These actions represent a deliberate and final turning away from the truth.

The God of the Old Testament is the God of the New. We cannot expect to exploit God’s mercy without consequence. Grace is not a license for carelessness; it is the power to live a holy life. To treat the sacrifice of Christ lightly, by wilfully continuing in sin after receiving knowledge of the truth, is to insult the Spirit who applies that sacrifice to us. Under the New Covenant, God’s law is written on our hearts, and the Holy Spirit is given to empower obedience. Therefore, to disregard this is a more serious offence. We are called to clear out the old leaven and worship Him with the unleavened bread of sincerity and truth.

A Call to Humility

Jesus Himself used an Old Testament event to illustrate salvation. In Numbers 21, the Israelites grumbled against God and Moses, and God sent poisonous snakes among them. The people began to die from the venomous bites. When they repented and cried out for mercy, God did not take the snakes away, but provided a cure. He instructed Moses to place a bronze serpent on a pole, so that anyone who was bitten could look at it and be healed. Jesus referred to this:

‘“As Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up; so that whoever believes will in Him have eternal life.”’ (Jn 3:14-15, NASB 1995)

The cure was to look in faith toward the image of their affliction. God’s solution involved lifting up an image of the thing that was causing death. In the same way, Jesus, who knew no sin, was “made to be sin on our behalf” (2 Cor. 5:21) and was lifted up on the cross. God did not remove the sting of death from the world; He provided an antidote in His Son, so that anyone who comes to Him in faith can find life.

This salvation, however, should lead to humility, not arrogance. Paul, in his letter to the Romans, uses the image of an olive tree to warn Gentile believers against pride. He describes Israel as a cultivated olive tree and the Gentiles as branches from a wild olive tree. Some of the natural branches were broken off because of unbelief, and the wild branches (Gentiles) were grafted in and given access to the root of God’s covenant promises to Israel. The root supports the branches, not the other way around. Salvation for Gentiles is a participation in the promises made to Abraham, Isaac, and Jacob.

‘Do not be conceited, but fear; for if God did not spare the natural branches, He will not spare you, either. Behold then the kindness and severity of God; to those who fell, severity, but to you, God’s kindness, if you continue in His kindness; otherwise you also will be cut off.’ (Rom. 11:20-22, NASB 1995)

This is a call to a faith that is active and persevering, recognising that our position is one of grace, which should be met with humble gratitude, not pride. The Old Testament is not a collection of outdated stories. It is an essential and living source of instruction, warning, and revelation about Christ, written for the benefit of all believers. It reveals the character of God, the nature of humanity, the consequences of sin, and the unfolding promise of a Saviour. To neglect it is to neglect the foundation of God’s revelation to us.