1Acts 2:24–25; Rom 1:4; cf. Rom 4:25; Heb 9:14; ²Acts 20:28; Heb 9:14; 7:25–28; ³Rom 3:24–26; ⁴Eph 1:6; Mt 3:17; ⁵Tit 2:13–14; ⁶Gal 4:6; ⁷Lk 1:68–69, 71, 74; ⁸Heb 5:8–9; 9:11–15.

The Word of God teaches us that "there is one God, and one mediator between God and men, the man Christ Jesus" (1 Tim 2:5). Why is there only one Mediator? Because only the Lord Jesus Christ qualifies to be the Mediator between God and Man, He being the God-Man, and is fully God and fully Man, being one person in two distinct natures forever. But why must this be so? Why must He be God? Why is the verity that Christ is God crucial to true Christianity? And why must He be man? Why is it important that His humanity be insisted upon? These are the questions that are addressed in the present and the next study.

First, God’s wrath against sin is an infinite wrath. The psalmist is not exaggerating when he declares: "If thou, LORD, shouldest mark iniquities, O Lord, who shall stand?" (Ps 130:3). No mere man can withstand the wrath of God against even the slightest sin such as an idle word (cf. Mt 12:36). The Mediator between God and man must bear the sin of the Church throughout the ages. Were He not God, His human nature would have been crushed under the wrath of God, for justice requires that He suffer infinite punishment in order to be a propitiation for His people. Were He not a divine Person, He would not be able to sustain the infinite wrath of God; and not only so, He would have to be holden under the power of death and suffer the wrath of God for all eternity (cf. Acts 2:24).

Secondly, the Mediator must be God in order to "give worth and efficacy to His sufferings, obedience, and intercession." If he were a mere sinful man, like Moses, Abraham or David, his suffering would not even be sufficient to pay for his own sins, not to mention paying for the sins of others. Even supposing, as a mere man, he was kept from sin, original and actual, by the power of the Spirit of God, he would still not qualify to be a Mediator, for his righteousness would then only be sufficient for himself and his sufferings would only be sufficient to pay for the sin of one other person.

The Lord Jesus Christ qualifies to be the Mediator, because He is not only sinless Man, but infinite God. Only the blood of a divine man is sufficient to pay for the sin of the Church. The apostle Paul hints at this fact when he refers to the Church of God as that "which he [i.e. God] hath purchased with his [i.e. God’s] own blood" (Acts 20:28).

Moreover, the fact that Christ is God also makes his intercession perfectly efficacious, whereas, it is impossible for mere man to know the will of God perfectly and therefore to intercede perfectly on behalf of the Church.

And thirdly, on the basis that the atonement, obedience and intercession of a divine mediator is alone efficacious for the Church, we learn that only if the Mediator is God can He "satisfy God’s justice, procure His favour, purchase a peculiar people, give His Spirit to them, conquer all their enemies, and bring them to everlasting salvation." If our mediator is not God, God’s justice will be violated if we are reconciled on the basis of His work; God’s favour could not be procured; His blood will not be sufficient to purchase a peculiar people; there will be no ground to send the Spirit of Christ; and we can have no hope of everlasting salvation.

In addition, moreover, to the reasons given in the Answer, we may surmise on two other reasons why the Mediator must be God. Firstly, the Mediator must be God, else we would have no representative in the "everlasting covenant" (Heb 13:20). If Christ were a mere man, he did not exist until the fullness of time. Therefore he could not represent us in the counsel of the Godhead, and there would be no basis for our election and love in him. Secondly, the Mediator must be God because we are debtors to God and when a creditor forgives a debt, he must necessarily bear the debt himself or there is no reconciliatory forgiveness. If our mediator were not God, then suppose his atonement was efficacious, he would be a third party paying for our sin, which would then imply that God’s justice is satisfied, but there is no personal or reconciliatory forgiveness (cf. 2 Cor 5:18-19).

All these points together, makes it essential that our Mediator be fully God. Were he not God, there is no atonement, no justice, no reconciliation and no forgiveness, which things are essential to true Christianity. W