Westminster Project 8.1

It pleased God, in his eternal purpose, to choose and ordain the Lord Jesus, his only begotten Son, to be the mediator between God and mankind - the prophet, priest, and king, the head and saviour of his Church, the heir of all things, and the judge of the world. From all eternity he gave to the Lord Jesus a people to be his seed and eventually to be redeemed, called, justified, sanctified, and glorified by him.
(WCF 8.1)

Humanity has always needed someone to stand in our place and plead our case before our great Creator God.
Job once cried out: “If only there were a mediator between us, someone who could bring us together… Then I could speak to him without fear, but I cannot do that in my own strength” (Job 9:33–35, NLT). That has always been the cry of God’s people: We want to know our Creator. We want to have friendship with Him. We want to speak to Him. But that is utterly and completely impossible in our own strength (Ps. 24:3–4; Rom. 10:6).

But praise be to God! By His grace and mercy alone, He condescended to us, becoming man in the person of Jesus Christ, to be exactly what we so desperately need (1 Tim. 2:5).
And why did He choose to do this? Because it pleased God, in His eternal purpose, to choose and ordain the Lord Jesus—His only begotten Son—to be the Mediator between God and mankind. In other words, while humanity longs for friendship with God, God also desires friendship with us. And though we were powerless to change our situation, God was not. He acted—by sending His only begotten Son (John 3:16).

So, what is the role of a mediator? And what is the role of Jesus?
In human terms, a mediator is someone independent of two parties who helps them negotiate and resolve disputes. Biblically, under the Law, God appointed ‘mediators’ who could represent both God and His people, pleading their case on their behalf. The most obvious example under the old covenant was the priest, who stood in the temple courts offering sacrifices and pleading for forgiveness with the blood of bulls and goats (Heb. 10:4).

Another mediating office was that of the prophet—one who heard from God and delivered His message (Isa. 6:8; Jer. 1:4–5). Perhaps the least understood was the king of Israel, who was raised up not only to lead and protect, but to feed God’s people with His Word (Deut. 17:18; 31:24–27). The problem with all of these men, however, is that they were sinners, and they died. They could not mediate forever—this was certainly the case with our first mediator, Adam (Gen. 2:17; Rom. 5).

That is why it is so important to see that Jesus came and fulfilled all these roles in Himself.
He is the greatest Prophet (Deut. 18:15–19; Acts 3:22), the greatest High Priest (Ps. 110:4; Heb. 5:1–5), and the greatest King (Ps. 110:1–2; Luke 1:33). And here is the key: because He never once sinned, death could not be His final judgment. Jesus rose again and continues in those roles for His people to this very day. Or, as the confession puts it: He is the Head and Savior of His Church, the heir of all things, and the Judge of the world.

Because of the grace, mercy, and compassion of God, we now have—at this very moment—a perfect Mediator who stands in the place of sinners, pleading our case with His perfect, sinless life.
And on the other side, when we approach the throne of grace in prayer, we are welcomed and heard—because we are seen as children of the Most High (Heb. 4:14–16). Believe it or not, this was always God's plan for His people: from all eternity, He gave to the Lord Jesus a people to be His seed—redeemed, called, justified, sanctified, and glorified by Him.