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Core Christianity: Tough Questions Answered

How Do We Know Jesus Is Our Mediator? {Lord’s Day 6}

by William Boekestein posted February 10, 2022

This article is part of our weekly series, “Our Life’s Comfort: One Year of Being Shaped by the Scriptures.” Read more from the series here.


(16) Q. Why must the mediator be a true and righteous man?
A. Because God’s justice requires that human nature, which has sinned, must pay for its sin; but a sinner could never pay for others.

(17) Q. Why must he also be true God?
A. So that, by the power of his divinity, he might bear in his humanity the weight of God’s wrath, and earn for us and restore to us righteousness and life.

(18) Q. Then who is this mediator—true God and at the same time a true and righteous man?
A. Our Lord Jesus Christ, who was given to us for our complete deliverance and righteousness.

(19) Q. How do you come to know this?
A. The holy gospel tells me. God himself began to reveal the gospel already in Paradise; later, he proclaimed it by the holy patriarchs and prophets and foreshadowed it by the sacrifices and other ceremonies of the law; and finally he fulfilled it through his own beloved Son.


The Bible is a like a mystery book. Paul uses the word mystery over a dozen times to describe how the gospel reveals Jesus. Here is the enigma: A just and merciful God made people to glorify and enjoy him. But they chose to rebel and make themselves and their posterity eternally miserable. God is just so he can’t dismiss sin. How then can we be saved?

That “mystery” has been “kept secret for long ages.” But it has “now been disclosed and through the prophetic writings has been made known to all nations” (Rom. 16:25). The solving of the mystery is “Christ in you, the hope of glory” (Col. 1:27). But salvation is no less mysterious than the problem it solves. “Great indeed is the mystery of godliness: [God] was manifested in the flesh” (1 Tim. 3:16). The gospel is the answer to the seemingly unsolvable human problem. In his beloved Son God has provided a mediator, one who stands in our place to receive the penalty we deserve. But how can we be certain that this is so?

How Do We Know Jesus Is Our Mediator?

Simple answer: the gospel! The gospel counters the law’s condemnation. “How do you come to know your misery? The law of God tells me” (QA 3). The law says, “Do this and you will live.” And that requirement has always been reasonable. God made humanity able to do what he required. But that way of life has become a way of death for us because we don’t obey God.

The gospel’s message of hope about a mediator who will “earn for us and restore to us righteousness and life” has been unfolding since the fall. It is the theme of good news running through the whole Bible.

The gospel is present in the Old Testament. “Good news came to us”—New Testament believers—“just as to them”—Old Testament believers (Heb. 4:2). “God himself began to reveal the gospel already in Paradise.” God told Satan, “I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel” (Gen. 3:15; see Rom. 16:20). That promise is mysterious. But the godly held to it as the only hope they had. “Later, [God] proclaimed [the gospel] by the holy patriarchs and prophets and foreshadowed it by the sacrifices and other ceremonies of the law.” The patriarch Abraham acted out the gospel by sacrificing a ram in the place of his son on the same hill on which later Jesus would offer himself in the place of lost sheep (Gen. 22:9–14). The prophet Isaiah preached that God would place upon his Servant the iniquity of us all (Is. 53:6). To Jesus “all the prophets bear witness that everyone who believes in him receives forgiveness of sins through his name” (Acts 10:43). Through grisly repetition the sacrifices of the law taught that blood shed on the altar makes atonement for sin (Lev. 17:11). Not that blood. Not that altar. But the message would be proved true in a single perfect sacrifice.

The gospel is performed in the New Testament. The people of Jesus’ day searched the Scriptures for a formula for eternal life—what must we do to make God accept us? But Jesus told them that they “bear witness about me” (John 5:39). Jesus fulfilled every prophecy. He was born of a virgin (Is. 7:14) into the tribe of Judah in the little town of Bethlehem (Mic. 5:2). “He was oppressed, and he was afflicted, yet he opened not his mouth” (Is. 53:7). He was buried like a wicked man in the grave of a rich man (9). But because of his righteousness his soul was not abandoned to Sheol (Ps. 16:10). He arose to scatter his enemies (68:1). He shattered the oppressor’s rod so that the people rejoiced (Is. 9:3–4).

Jesus is the mediator promised since the beginning, the seed of the woman who broke Satan’s choke-hold on God’s people. This is a synopsis of the Bible. But we might zoom in and ask a more detailed question.

What Qualifies Jesus to Be Our Mediator?

Or more practically, why can I trust him?

First, he is “a true and righteous man.” “That human nature, which has sinned, must pay for its sin.” Jesus is not nearly like us. He is fully like us, “made like his brothers in every respect” (Heb. 2:17). The church fathers at the Council of Chalcedon reaffirmed the Nicene Creed which states that “our Lord Jesus Christ … God of God … was made man.” But in response to several heresies about Jesus’ manhood (he only appeared to be human, or was a strange concoction of deity and humanity) they offered this clarification: Jesus is “consubstantial (of the same substance) with us according to the Manhood.” Jesus is not only truly human; he is more perfectly human than we who have become deformed by sin. Christ is exactly the representative we need. “It was fitting that we should have such a high priest, holy, innocent, unstained, separated from sinners, and exalted above the heavens” (Heb. 7:26).

Second, he is “true God.” He is “consubstantial with the Father according to the Godhead,” as the fathers at Chalcedon put it. Christ suffered for us in his perfect humanity. Even before it happened he knew that the punishment of every child of God would be placed on his precious head. When he wrestled with what this would mean he sweat great drops of blood (Luke 22:44). But he was able to endure eternal torment “by the power of his divinity.” His divinity didn’t mute his suffering. In fact being God he could fully experience the terrors of God’s wrath without being overwhelmed.

Third, he “was given to us for our complete deliverance and righteousness.” God’s salvation perfectly fits our needs. We are enslaved to sin and Satan and owe God a debt of righteousness we can never repay. But Jesus is a complete Savior. The gospel isn’t just an invigorating message that urges us to try harder. It is the record of God’s total rescue of his people. Christ truly “earn[s] for us and restore[s] to us righteousness and life.” The Lord is our salvation! Only this message can make us fall on our faces in awe of his majesty and wholeheartedly commit ourselves to his loving service. The law said, “You are dead.” The gospel assures us that because of Christ, like him, we are alive forevermore (Rev. 1:18).

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