Christ the Mediator and the Testator of the Covenant

By Nick Bibile

Who hath saved us, and called us with an holy calling, not according to our works, but according to his own purpose and grace, which was given us in Christ Jesus before the world began.”
2 Timothy 1:9


I. The Acts of God: External and Internal

The acts of God may be distinguished into two categories:

1. External Acts of God

These are God’s works revealed in time, visible to His creatures who live within time. They include:

2. Internal Acts of God

These are God’s eternal acts, performed within Himself, before time began. They are invisible to us unless God reveals them by Scripture. These eternal counsels were once hidden but are now made known:

Having made known unto us the mystery of his will, according to his good pleasure which he hath purposed in himself.”
Ephesians 1:9

Election belongs to these internal acts of God, for it took place in eternity. The elect were chosen in Christ, before the foundation of the world.

According as he hath chosen us in him before the foundation of the world…”
Ephesians 1:4–6

John Owen writes:

All the acts of God toward the elect are but the execution of His eternal purpose, which He purposed in Christ Jesus before the world began.”
The Death of Death in the Death of Christ


II. The Eternal Counsel of God and the Covenant of Grace

Internal acts belong to the divine mind. Within the Trinity there were eternal transactions—holy counsels and agreements—concerning the salvation of sinners.

The counsel of the LORD standeth for ever, the thoughts of his heart to all generations.”
Psalm 33:11

The Covenant of Grace is one such internal act. It was not devised in time but established in eternity. It is an eternal compact among the divine Persons, planned in heaven before the world existed.

I have said, Mercy shall be built up for ever: thy faithfulness shalt thou establish in the very heavens.”
Psalm 89:2

Herman Witsius states:

The covenant of grace is an eternal transaction between the Father and the Son, concerning the salvation of the elect.”
The Economy of the Covenants

This covenant is firm, unchangeable, and everlasting:

My mercy will I keep for him for evermore, and my covenant shall stand fast with him.”
Psalm 89:28


III. Christ the Seed and Head of the Covenant People

The saints—the elect church—come from the seed of Christ, the promised Messiah.

I will put enmity between thee and the woman, and between thy seed and her seed…”
Genesis 3:15

This seed was promised from the beginning and fulfilled in Christ.

The mercy of the LORD is from everlasting to everlasting upon them that fear him.”
Psalm 103:17

John Calvin says:

Christ is the foundation of the covenant, and apart from Him no grace flows to men.”
Institutes, II.10.2


IV. The Father’s Design and Christ’s Mediatorial Obedience

Redemption was planned by God the Father, designed in eternal counsel, and entrusted to the Son. The Father gave Christ a commandment; Christ willingly accepted the office of Mediator.

This commandment have I received of my Father.”
John 10:18

That the world may know that I love the Father; and as the Father gave me commandment, even so I do.”
John 14:31

Stephen Charnock writes:

The Father contrived salvation, the Son accomplished it, and the Spirit applies it.”
Discourses Upon the Existence and Attributes of God


V. Christ Given as the Covenant of the People

Christ was not merely a messenger of the covenant—He is the covenant itself.

I will give thee for a covenant of the people, for a light of the Gentiles.”
Isaiah 42:6

This covenant relationship is illustrated by marriage. Christ is the Husband; the church is His bride, given to Him by the Father before the world began. Though the elect fell into sin, Christ came to redeem what was eternally His.

Christ loved the church, and gave himself for it.”
Ephesians 5:25

Samuel Rutherford says:

Christ’s love to His bride is older than time, deeper than sin, and stronger than death.”


VI. Christ the Head and Mediator of the Covenant

Christ is the Head of the Church, supplying life, grace, and nourishment to every member.

And gave him to be the head over all things to the church.”
Ephesians 1:22–23

He is also the only Mediator between God and men:

For there is one God, and one mediator between God and men, the man Christ Jesus.”
1 Timothy 2:5

Thomas Goodwin writes:

Christ stands between God and us, receiving from God and conveying to us all covenant blessings.”


VII. Christ the Testator of the Covenant

The Covenant of Grace is executed in the form of a Testamenta sovereign declaration of God’s will. Hence we have the Old Testament and the New Testament. The substance of the covenant remains the same; only the administration differs.

In the Old Testament, the covenant was administered through types and shadows; in the New Testament, through fulfillment in Christ.

For where a testament is, there must also of necessity be the death of the testator.”
Hebrews 9:16

Christ is both Testator and Sacrifice. The elect are His inheritance:

The LORD’S portion is his people.”
Deuteronomy 32:9

Ask of me, and I shall give thee the heathen for thine inheritance.”
Psalm 2:8


VIII. The Seal of the Covenant

The covenant is sealed not by circumcision nor by baptism, but by the Holy Spirit and the blood of Christ.

After that ye believed, ye were sealed with that holy Spirit of promise.”
Ephesians 1:13

This is my blood of the new testament.”
Matthew 26:28

John Flavel writes:

The blood of Christ is the golden seal of the everlasting covenant.”


IX. Sovereign Pleasure and the Proper Response

Why did God save any?
Why did He give His Son?
Why does He save some and not others?

There is one answer:
His sovereign pleasure.

Even so, Father: for so it seemed good in thy sight.”
Matthew 11:26

Jonathan Edwards states:

God’s sovereignty is absolute, His grace free, and His mercy unmerited.”

These doctrines must lead us to humility, not pride. Either they puff us up, or they bring us low before God. True understanding produces love, patience, and reverence.

That no flesh should glory in his presence.”
1 Corinthians 1:29

We are nothing—less than nothing—apart from grace. And yet God has shown us mercy in Christ. Therefore, let us adore Him with humility, teach others with love, and glory only in the Lord.

He that glorieth, let him glory in the Lord.”
1 Corinthians 1:31