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 been in need of 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 totally and utterly impossible in our own strength (Ps 24:3-4, Rom 10:6).
Well praise be to God, by His grace and mercy alone, He condescended to us, becoming man in Jesus Christ so as to come and be that very thing we very much need (1 Tim 2:5). And why did He so choose to do that? It was 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, humanity needs and desires friendship with God, but on the flip side, God desires and wants friendship with us too. And though it was impossible for humanity to do anything about it, God could, and He did in sending His only begotten Son (Jn 3:16).
And so what is the role of a mediator? And what is the role of Jesus? Humanly speaking a mediator is someone independent of two parties that assists in negotiations or agreements to resolve disputes. Biblically speaking, God set up ‘mediators’ under the law that could stand for God and stand in our place simultaneously, pleading our case under the law. The most obvious ‘mediator’ under the old covenant was the priest. They would stand in the tabernacle/temple courts pleading forgiveness with the blood of bulls and goats (Heb 10:4). Another such office was the prophet, who would hear from God and deliver messages on His behalf (Isa 6:8, Jer 1:4-5) and maybe the least understood was the king of Israel, a man who was raised to not just lead and protect, but feed God’s people His Word (Deut 17:18, 31:24-27). The problem with all these men is that they were sinners and died - they couldn’t mediate for long, that was certainly the case with our first mediator Adam (Gen 2:17, Rom 5).
That is why it is important that we see that Jesus came and fulfilled all those roles in Himself. He was is greatest prophet (Deut 18:15-19; Acts 3:22), He is the greatest High Priest (Ps 110:4; Heb 5:1-5), and He is the greatest king (Psalm 110:1-2; Lk 1:33) - and this is the thing - because He never once sinned, death couldn’t be His final judgment, and so Jesus continues in those roles for His people to this very day, or as the confession puts it, he is the head and saviour of his Church, the heir of all things, and the judge of the world.
Because of the grace and mercy and compassion of God, we have (at this very moment) a perfect mediator that stands in the place of sinners, pleading our case with His perfect sinless life. On the other side of things, 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). And believe it or not, this was always the plan for God’s people as, 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.