Devotional 41: The Mediator of the Covenant: Jesus Christ, the Surety

The Confession Read

This covenant of grace is frequently set forth in Scripture by the name of a testament, in reference to the death of Jesus Christ the Testator, and to the everlasting inheritance, with all things belonging to it, therein bequeathed.

— Westminster Confession of Faith, Chapter 7, Section 4

Introduction

A family gathers in a solicitor's office on a grey November afternoon. The patriarch has died, and the will is about to be read. For years the document sat in a strongbox, its provisions hidden, its promises sealed, its authority suspended. For a last will and testament has a strange and absolute property: it speaks, but it does not act until the one who signed it has breathed his last. While the testator lived, the ink on the page conferred nothing. The beneficiaries could know the will existed; they could hope in its promises; they could even hold a copy in their hands. But they could not touch a single shilling of the inheritance. The death of the testator was the key that turned in the lock, the event that transformed words on paper into property in hand. Without death, the testament was a dead letter. With death, it became irrevocable law. The Westminster Divines, in the fourth section of their chapter on God's covenant with man, invite us to see the gospel through precisely this lens. The covenant of grace, whose substance they set forth with such compressed brilliance in Section 3, the free offer of life and salvation by Jesus Christ, the requirement of faith, the promise of the Spirit to make the unwilling willing and the unable able — this same covenant, they now observe, is called in Scripture by another name. It is called a testament. And the name is not incidental. It is chosen by the Holy Spirit to teach us something about the death of Jesus Christ that the bare language of covenant, rich as it is, does not fully capture. The death of Christ was not a tragic interruption of His ministry, an unfortunate setback later reversed by resurrection. It was the very hinge on which the whole economy of grace turns. Without it, the covenant remains a sealed document, a promise unfulfilled, a hope without substance. With it, the everlasting inheritance is irrevocably, immovably, and eternally ours. We have seen, across the first three sections of this chapter, the architecture of God's covenantal dealings with men: the infinite distance that only voluntary condescension can bridge, the covenant of works made with Adam and broken, the covenant of grace freely offered to sinners. Each step has added a beam to the structure. Now the Divines add the keystone, and it is a word no one expected: testament. Not a treaty between equals. Not a contract negotiated at arm's length. A last will and testament, drawn up by the Father, executed by the Son, and applied to the heirs by the Spirit, in which the sole condition of the inheritance, the death of the Testator, has been fully and finally met.

Scripture Foundation

The Confession's claim that the covenant of grace is "frequently set forth in Scripture by the name of a testament" rests on a single word that carries within it the entire architecture of our redemption. That word is the Greek diatheke, and its dual meaning opens a door into the heart of the gospel. The author of the epistle to the Hebrews provides the definitive exposition, and no passage in Scripture rewards closer attention on this theme than the one with which we must begin. Hebrews 9:15-17 — "And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance. For where a testament is, there must also of necessity be the death of the testator. For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth." The logic is inexorable, and it proceeds on a single linguistic observation. The Greek word diatheke can mean either "covenant" (a bilateral arrangement between parties, like a treaty) or "testament" (a unilateral disposition of goods taking effect at death, like a last will). Hebrew has no exact equivalent for the latter sense; the Hebrew berith always means covenant. But the authors of the Septuagint chose diatheke to translate berith, and the Holy Spirit, in inspiring the New Testament, exploited the semantic range of that Greek word to reveal a truth that Hebrew alone could not express. The covenant of grace is a diatheke in both senses: it is a sovereignly arranged covenant in which God binds Himself to bless His people, and it is a testament in which the blessings are bequeathed through death. The author of Hebrews drives the point home with an analogy drawn from ordinary human experience: a testament has no legal force while the testator lives. The Greek is vivid — epei me tote ischuei — "since it is not then in force." A will sitting in a drawer confers nothing. The heirs may read it, may treasure its promises, may build their hopes upon it, but until the testator dies, the inheritance remains a future prospect, not a present possession. The death is the indispensable condition. And this, the author argues, is why Christ had to die. He is not merely the Mediator of a covenant; He is the Testator whose death activates the testament. The redemption of transgressions, the forgiveness of sins committed under the first covenant, could not be accomplished by a living Christ but only by a dying One. Until Calvary, the inheritance of eternal life was promised but not yet paid for, held out but not yet legally transferred. The cross was the moment when the Testator died and the testament passed from promise to power. But Hebrews does not leave the matter there. A few verses earlier, the same author had already established the better character of this testament by comparison with the old. Hebrews 8:6 — "But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises." The Greek behind "covenant" here is again diatheke, and the context makes clear that the author moves freely between the covenantal and testamental meanings, drawing from each what the other cannot supply. The new diatheke is better — the Greek kreittonos is a comparative that runs through Hebrews like a golden thread — because its promises are unconditional, its mediator is divine, and its foundation is not the blood of bulls and goats but the blood of the Testator Himself. Our Lord Jesus Christ, on the night in which He was betrayed, chose His words with the precision of One who knew exactly what the next day would bring. Matthew 26:27-28 — "And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the new testament, which is shed for many for the remission of sins." Every clause carries theological weight. "My blood" — not the blood of animals, which could never take away sin, but the blood of the Son of God. "Of the new testament" — the Greek is hē kainē diathēkē, the new testament-covenant, the eschatological arrangement prophesied by Jeremiah, now inaugurated not with the blood of calves but with the blood of the incarnate Lord. "Shed for many" — the preposition peri with the genitive indicates representation, substitution. His blood is poured out on behalf of the many, in their place, for their benefit. "For the remission of sins" — the Greek aphesis means release, forgiveness, the cancellation of a debt. And the whole complex of blessings is tied to His death. He did not say, "This is my teaching which shall be given for the instruction of many." He said, "This is my blood." The testament takes effect at death, and the death is hours away. The apostle Paul adds a further dimension to the testamental logic by connecting it to the unchangeable character of the inheritance. Galatians 3:15-18 — "Brethren, I speak after the manner of men; Though it be but a man's covenant, yet if it be confirmed, no man disannulleth, or addeth thereto. Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ. And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect. For if the inheritance be of the law, it is no more of promise: but God gave it to Abraham by promise." Paul's word for "covenant" here is again diatheke, and the legal logic he employs is precisely that of a testament. A human testament, once ratified — the Greek kekyrōmenēn means legally validated, confirmed beyond challenge — cannot be set aside or modified by a later document. No one can add a codicil to a dead man's will. The inheritance that God promised to Abraham was a testamental inheritance, grounded not in law-keeping but in promise, and the law that came later at Sinai could not annul or amend it. The inheritance is by promise, not by performance, and the promise was confirmed, ratified, sealed, and made irrevocable, in Christ. When Paul says the covenant was "confirmed before of God in Christ," he is looking forward to the death that would make the testament effectual. The promise to Abraham was a promissory note drawn on the bank of Calvary. The note was payable at the death of the Testator. Finally, the apostle Peter gives us a glimpse of the inheritance itself, and the language shimmers with the joy of tested and triumphant hope. 1 Peter 1:3-5 — "Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead, To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you, Who are kept by the power of God through faith unto salvation ready to be revealed in the last time." Peter uses three adjectives to describe the inheritance, each one a negation of everything we know about earthly legacies. It is incorruptible — the Greek aphtharton means imperishable, immune to decay. Earthly inheritances rust, rot, and depreciate. Every human testament conveys goods that time will consume and death will finally separate from their owners. Not this inheritance. It is undefiled — the Greek amianton means unstained, unsoiled, free from any moral or ceremonial pollution. Earthly inheritances so often come with hidden debts, disputed titles, and guilty origins. Not this inheritance. It is unfading — the Greek amaranton is drawn from the image of a flower that never withers. The beauty of every earthly possession fades; the joy of every earthly gift dims with familiarity and time. But the inheritance bequeathed by the dying and rising Testator knows no decay, no stain, no fading. And it is reserved — the Greek tetērēmenēn is a perfect passive participle, meaning it has been laid up and remains laid up, kept under guard, secured against every threat. The Testator who died to bequeath it now lives to guard it, and no power in heaven or earth or under the earth can touch what He has secured.

What the Divines Meant

When the Westminster Assembly gathered in the 1640s to frame a confession for the three kingdoms, the relationship between covenant and testament was not a matter of abstract linguistic curiosity. It touched the very heart of the gospel, and the errors the Divines were answering made the precision of this section pastorally urgent. The first and most obvious target was Rome. The Council of Trent had declared the Mass to be a true and proper sacrifice for the living and the dead, a propitiatory offering in which Christ is offered anew by the priest. This doctrine struck at the root of the testamental character of the new diatheke. If the Mass re-presents or re-offers Christ, then His death on Calvary was not the once-for-all death of the Testator that brings the testament into perpetual force. It becomes, instead, a death that must be repeated, re-enacted, re-applied by human agency. The author of Hebrews had already dismantled this error in advance: "Nor yet that he should offer himself often... but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself. And as it is appointed unto men once to die, but after this the judgment: So Christ was once offered to bear the sins of many." The Divines, by insisting that the covenant of grace is a testament in reference to the death of Christ the Testator, were guarding the finality of the cross. A testament takes effect once, at the death of the testator. It cannot be re-executed. The blood of the new testament was shed once, and that one shedding is sufficient for all the sins of all the elect for all time. The second error was Socinianism, which denied that the death of Christ was a satisfaction for sin. The Socinians taught that Christ died as a martyr, an example of obedience and love, a confirmation of His teaching, but not as a sacrifice that propitiated divine wrath or paid a legal penalty. The testamental language of Hebrews 9 answers this comprehensively. If Christ's death was merely exemplary, why does the author insist that a testament requires the death of the testator? Why the "necessity" (the Greek anagkē means unavoidable necessity, not optional preference) of death? A martyr's death does not activate a testament. Only the death of a testator does. And the inheritance bequeathed is not moral inspiration but redemption, forgiveness, eternal life. The Socinian Christ could not bequeath these things because He did not purchase them. The Christ of the Confession did. The third error was a subtler one, arising within Protestant circles that over-emphasized the conditional character of the covenant. Some theologians, reacting against antinomianism, spoke of the covenant of grace in terms that made it sound like a contract: God promises salvation on condition of faith, and if the sinner performs the condition, God is bound to perform His part. There is a truth here: the Confession itself says God offers salvation "requiring of them faith in him, that they may be saved." But the testamental language supplies a necessary correction. A testament is not a contract between equals. It is a unilateral disposition by which the testator freely bestows his goods upon beneficiaries who have done nothing to earn them and can do nothing to alter the terms. The heirs of a will do not negotiate. They do not fulfill conditions that activate the bequest. They receive, freely and unconditionally, what the testator has chosen to give them. The covenant of grace, considered as a testament, is the freest thing in the universe. The only condition, the death of the Testator, has been met by the Testator Himself. The Divines chose every word with care. "Frequently set forth" — the language is not occasional but pervasive, a recurring pattern in the New Testament's presentation of the gospel. "In reference to the death of Jesus Christ the Testator" — the death is not an afterthought, not a tragic accident, but the central reference point of the whole arrangement. And "the everlasting inheritance, with all things belonging to it, therein bequeathed" — the scope is comprehensive. Not some blessings, not partial benefits, not probationary gifts that can be lost, but an everlasting inheritance with everything that belongs to it. The Divines are teaching us that the cross is not merely the instrument of our forgiveness but the legal mechanism by which every spiritual blessing in the heavenly places is transferred from Christ to His people.

Theological Depth

The Reformed tradition has probed the testamental character of the covenant of grace with an intensity born of the conviction that here, in a single Greek word and its dual meaning, the Holy Spirit has compressed the entire logic of redemption. John Owen, in his monumental commentary on Hebrews, devotes sustained attention to the distinction between diatheke as covenant and diatheke as testament. Owen observes that the covenant of grace is a testament in three precise respects. First, it is the free disposition of the goods of the testator: Christ disposes of His righteousness, His Spirit, His peace, His glory, to those who have no claim upon any of them. Second, it is confirmed by the death of the testator: the blood of Christ is the seal that makes the testament irrevocable. Third, it bequeaths an inheritance that the testator Himself, having died and risen, now administers as the living Lord who was dead and is alive forevermore. Owen presses the logic to its pastoral conclusion: if Christ's death was the death of a testator, then every promise of the gospel carries the force of a dead man's will, which no court in heaven or earth can overturn. The believer's security rests not on the strength of his faith but on the unalterable testament of a Testator who cannot die again. Herman Witsius, in his Economy of the Covenants, takes up the same theme and develops it with systematic precision. Witsius distinguishes between the covenant of grace considered broadly, as the eternal agreement between the Father and the Son for the redemption of the elect — the pactum salutis, the covenant of redemption — and the covenant of grace considered strictly, as its temporal administration in which the benefits purchased by Christ are applied to the elect. In the former sense, diatheke is a covenant properly so called, with mutual stipulations between the persons of the Godhead. In the latter sense, diatheke is a testament, a free bequest of goods to unworthy heirs. Witsius argues that this double meaning is not a linguistic accident but a theological providence. The Holy Spirit chose a word that could carry both senses because the reality itself demands both. The eternal transaction between Father and Son required covenantal language; the free bestowal of its benefits upon sinners required testamental language. The single word holds together what no single English word can: the sovereign arrangement by which redemption was accomplished and the gracious mode by which it is received. Geerhardus Vos, whose biblical-theological instincts consistently opened fresh vistas in familiar texts, emphasizes the eschatological force of the testament concept. A testament, Vos observes, is inherently forward-looking. It is drawn up in the present but its benefits are enjoyed in the future, after the death of the testator. The old covenant saints lived in the period between the drafting of the testament and the death of the Testator. They had the promises, the types, the shadows; they could read the will, as it were, and trust its provisions. But they could not receive the inheritance because the Testator had not yet died. The blood of bulls and goats could not activate the testament; only the blood of Christ could. This is why Hebrews says that Christ's death provided "redemption of the transgressions that were under the first testament." The sins of Old Testament believers were forgiven on credit, so to speak — on the strength of a death yet to come, a testament yet to be activated. The cross was the moment when all those promissory notes came due and were paid in full. The entire history of redemption is the story of a testament waiting for a death. Robert Shaw, whose exposition of the Confession remains one of the most lucid guides to the mind of the Divines, draws attention to the phrase "with all things belonging to it." The inheritance bequeathed, Shaw notes, is not merely a future hope of heaven. It includes everything that belongs to that hope: the indwelling Spirit as the earnest of the inheritance, the forgiveness of sins as the clearing of the title, adoption as the legal status of an heir, sanctification as the progressive preparation of the heir for his inheritance, and perseverance as the guarantee that the heir will reach his destination. None of these blessings is purchased by the believer's efforts. All are bequeathed by the Testator's death. Shaw's point is pastoral: the believer who feels poor in grace, weak in faith, and slow in sanctification must not imagine that these deficiencies cancel his inheritance. The inheritance depends on the Testator's death, not the heir's worthiness. And the Testator has died. Thomas Goodwin, one of the Westminster Divines themselves, explores the emotional and spiritual logic of the testament concept with characteristic warmth. Goodwin observes that a testament, by its very nature, is an instrument of love. A man makes a will because he loves his beneficiaries and desires their welfare after his departure. The testament of Christ is the expression of an eternal love that death could not extinguish but only activate. And there is this further comfort: the death of a testator is not the end of the relationship. Under human law, the testator dies and his executors administer the estate. But Christ, the divine Testator, died and rose again. He is both the Testator whose death activated the testament and the living Lord who administers its blessings. The hands that were pierced to sign the will are the hands that now distribute the inheritance. Goodwin presses the logic to its limit: the believer's relationship to Christ is not like that of an heir to a dead benefactor, remembered with gratitude but incapable of ongoing fellowship. It is the relationship of an heir to a living Testator who loves him, prays for him, intercedes for him, and will one day come to bring him into the full possession of everything that the testament promised.

Puritan Application

First, learn to read your Bible with testamental eyes. The Scriptures are not merely a record of commands to obey and examples to follow. They are a testament — a document in which a dying Testator bequeaths an inheritance to His people. When you open the Gospels and read of Christ's words and deeds, you are reading the public ministry of the Testator in the days before His death, explaining the terms of the will He was about to seal with His blood. When you read the Epistles, you are reading the counsel of the executors He appointed, the apostles, applying the provisions of the testament to the lives of the heirs. When you read the promises, "I will never leave thee nor forsake thee," "I go to prepare a place for you," "I will come again and receive you unto myself," you are not reading vague assurances or hopeful wishes. You are reading the clauses of a legally binding testament, ratified by death, unalterable by any power in heaven or earth. This changes everything about how you handle the Word of God. You do not come to Scripture as a student to a textbook or an employee to a manual. You come as an heir to a will, to read what is yours, to understand what has been bequeathed to you, and to live in the confidence that every promise you find there is as certain as the death that sealed it. Second, anchor your assurance in the death of the Testator, not in the strength of your faith. It is a perennial temptation of the believing heart to look inward for evidence of its standing before God. We ask ourselves: Do I believe strongly enough? Do I repent deeply enough? Do I love Christ fervently enough? And because the answer to every such question is a variation on "Not enough, Lord; not nearly enough," we stagger and doubt and fear. But the testamental character of the covenant of grace answers this endless, exhausting introspection with a single, decisive truth. The validity of a will does not depend on the worthiness of the heir. It depends on the death of the testator. Your inheritance is not secured by the strength of your grip on Christ but by the reality of Christ's death for you. A trembling hand that receives a gift possesses it as truly as a steady hand. A weak faith in a strong Savior saves as certainly as a strong faith — because the saving power resides not in the faith but in the Savior. Owen, whose pastoral wisdom is nowhere more evident than here, counsels believers to stop measuring their faith and start looking at the cross. The death that activated the testament is an objective, historical, unalterable fact. The question is not "Do I feel saved?" but "Has Christ died?" And He has. Third, live in the liberty of an heir, not the anxiety of a probationer. There is a kind of Christian living that treats the Christian life as a second probation, a new covenant of works in which final salvation depends on the believer's faithfulness rather than on Christ's. Every stumble becomes a potential catastrophe. Every season of spiritual dryness raises the specter of lost salvation. Every sin threatens to annul the inheritance. But the testament of Christ admits no such anxieties. A testament is irrevocable. Once the testator has died, the inheritance belongs to the heirs by legal right, and no failure on their part, no sin, no weakness, no backsliding, can overturn what death has sealed. This is not an invitation to licentiousness; it is the death of licentiousness, because the one who knows how much has been forgiven loves much. But it is also the death of despair, because the one who knows that his inheritance depends on Another's death can face his own failures without fearing that he has forfeited everything. You are not on probation. The Testator has died. The testament is in force. The inheritance is yours. Live, then, not as a slave who must earn his keep but as a son who already possesses the whole estate. Let your obedience be the glad, free, grateful response of an heir, not the anxious, calculating self-protection of a wage-earner. Fourth, let the certainty of the inheritance sustain you through every trial. Peter tells us that the inheritance is "reserved in heaven for you," and the verb is in the perfect tense: it has been reserved and remains reserved, kept under guard by the power of God. Every earthly treasure is vulnerable. Markets crash. Thieves break in and steal. Moth and rust corrupt. Death strips us of everything we have accumulated. But the inheritance bequeathed by the Testator's death is beyond the reach of every enemy: beyond economic collapse, beyond political upheaval, beyond Satan's malice, beyond death itself. When your health fails, the inheritance holds. When your relationships fracture, the inheritance holds. When your ministry bears little visible fruit, the inheritance holds. When you stand at the graveside of someone you love, the inheritance holds. The resurrection of Jesus Christ from the dead is the guarantee, the down payment, the first installment, the irrefutable proof, that the full inheritance will be delivered. The Testator who died now lives, and because He lives, His heirs shall live also. Let this truth be the ballast in your keel when the storms come. They will come. But the inheritance will not fail. Fifth, and finally, remember that the Testator lives. Here the analogy with human testaments breaks down, and the breakdown is the gospel. A human testator dies and remains dead; his will is administered by others who may be incompetent or unfaithful. But the divine Testator died and rose. He administers His own testament. He is the Executor of His own will. Every blessing He bequeathed — forgiveness, adoption, sanctification, perseverance, glory — He Himself applies to His heirs by His Spirit. He is not a distant benefactor whose memory we cherish but a living Lord who walks with us, speaks to us in His Word, feeds us at His table, intercedes for us at the right hand of the Father, and will one day return to bring us into the full possession of everything He promised. The hands that were pierced to sign the testament are the hands that hold you now, and no one — no one — can pluck you from those hands. The inheritance is vast: a new heaven and a new earth, a resurrected body conformed to His glorious body, the beatific vision of God, an eternity of joy that will never fade. But the inheritance, great as it is, is not the greatest gift. The greatest gift is the Testator Himself. He is the inheritance, and to have Him is to have everything.

Prayer

O blessed Lord Jesus Christ, the Mediator of the new testament and the Testator whose death hath given it everlasting force, we bow before Thee with hearts too small to contain the wonder of what Thou hast done. Thou didst not come to be served but to serve, and to give Thy life a ransom for many. Thou didst take the cup on the night of Thy betrayal and call it the new testament in Thy blood, and on the morrow Thou didst pour out that blood upon the cross, sealing with Thy death every promise Thou hadst made. We bless Thee that the testament is now in force, irrevocable and unalterable, and that every blessing it contains is ours by right of Thy bequest. We confess, O Lord, that we have lived too often as paupers when we are heirs. We have doubted promises sealed by blood. We have looked to the weakness of our own faith rather than the certainty of Thy death. We have let the accusations of the enemy and the guilt of our own consciences drown out the witness of the Spirit, who testifies that we are children of God and joint-heirs with Christ. Forgive the smallness of our faith, and enlarge our hearts to receive the fullness of what Thou hast bequeathed. Teach us to live as those who possess an inheritance incorruptible, undefiled, and unfading, reserved in heaven for us. When trials press upon us, remind us that the inheritance holds. When sins accuse us, remind us that the Testator has died and the testament cannot be annulled. When death draws near, remind us that the Testator who died now lives and has gone to prepare a place for us, that where He is, there we may be also. Grant us grace to administer what Thou hast entrusted to us in this present life as faithful stewards, not clinging to earthly treasures that perish but holding them loosely and using them for Thy glory, knowing that the true riches await us in Thy presence. Make us cheerful givers, joyful servants, and patient sufferers, for the inheritance to come far outweighs the light and momentary afflictions of this present age. And we pray for those who are still strangers to the testament of grace, who have never fled to the Testator for refuge, who are trying to earn by their own works what can only be received by faith. O blessed Spirit, whose office it is to take what is Christ's and show it unto men, open blind eyes and raise dead souls. Show them that the testament is sealed, the inheritance prepared, the Testator willing, and nothing required of them but that they receive what Christ has purchased. Bring us at last, with all the redeemed of every age, to that day when faith shall give way to sight and hope to possession. Then shall we see Thee face to face, the Testator who died for us and lives for us, and we shall enter into the joy of our Lord, not as strangers admitted on sufferance but as heirs entering their own inheritance, purchased by blood, promised by grace, and delivered by the power of an endless life. Even so, come, Lord Jesus. Amen.