What is Christ the Mediator?
It pleased God, in His eternal purpose, to choose and ordain the Lord Jesus, His only Son, in accordance with the covenant made between them both, to be the Mediator between God and the human race; to be Prophet, Priest, and King; to be the Head and Saviour of His church, the Heir of all things, and Judge of the world. From all eternity He gave to Him a people to be His progeny. In time these would be redeemed, called, justified, sanctified, and glorified by Him.
The Son of God, the second person in the Holy Trinity, is truly and eternally God. He is the brightness of the Father's glory, of the same substance and equal with Him who made the world, who upholds and governs all things He has made.
When the fullness of time was come, He took upon Himself human nature, with all its essential properties and common infirmities, yet without sin. He was conceived by the Holy Spirit in the womb of the Virgin Mary. The Holy Spirit came down upon her and the power of the Most High overshadowed her, so that He was born to a woman from the tribe of Judah, a descendant of Abraham and David, in accordance with the Scriptures.
So two whole, perfect, and distinct natures were inseparably joined together in one person, without conversion, mixing, or confusion. This person is therefore truly God and truly human, yet one Christ, the only Mediator between God and the human race.
The Lord Jesus, His human nature thus united to the divine in the person of the Son, was sanctified and anointed with the Holy Spirit without limit, so in Him are all the treasures of wisdom and knowledge. It pleased the Father that all fullness should dwell in Him, so that being holy, harmless, undefiled, and full of grace and truth, He might be perfectly qualified to execute the office of a mediator and surety. He did not take this office upon Himself, but was called to it by His Father, who also put all power and judgment in His hands, and commanded Him to execute these.
The Lord Jesus undertook this office entirely willingly. To discharge it He was subject to the Lawand perfectly fulfilled it. He also underwent the punishment due to us which we should have borne and suffered.He was made sin and was accursed for us; He endured the extremities of agonizing distress in His soul and painful suffering in His body.He was crucified, and died, and remained in the state of the dead, yet His body did not decay.On the third day He rose from the dead with the same body in which He had suffered, with which He also ascended into heaven,where He sits at the right hand of His Father making intercession [for His people]. At the end of the world He will return to judge human beings and angels.
The Lord Jesus has fully satisfied the justice of Godby His perfect obedience and His once-for-all sacrifice which He offered up to God through the eternal Spirit.He has procured reconciliation, and has purchased an everlasting inheritance in the kingdom of heaven for all those whom the Father has given to Him.
Although the price of redemption was not actually paidby Christ till after His incarnation, yet its value, efficacy, and benefits were communicated to the elect in all ages from the beginning of the world. This was accomplished through those promises, types, and sacrifices in which He was revealed and represented as the seed of the woman who should bruise the serpent's head, and the Lamb slain from the beginning of the world,for He is the same, yesterday and today and forever.
In His work of mediation, Christ acts according to both natures, in each nature doing that which is appropriate to itself. Yet, because of the unity of His person, that which is appropriate to one nature is sometimes in Scripture attributed to the person indicated by the other nature.
To all those for whom Christ has obtained eternal redemption, He certainly and effectually applies and communicates this redemption,making intercession for them. He unites them to Himself by His Spirit, He reveals to them the mystery of salvation in and by the Word, He persuades them to believe and obey controlling their hearts by His Word and Spirit,and He overcomes all their enemies by His almighty power and wisdom using methods and ways which are perfectly consistent with His wonderful and unsearchable providence. All this is by free and absolute grace, without any foreseen condition in them to obtain it.
This office of Mediator between God and the human race belongs exclusively to Christ, who is the Prophet, Priest, and King of the Church of God. This office may not be transferred from Him to any other, either in whole or in part.
The number and order of offices is essential. Because of our ignorance we need His prophetic office. Because of our alienation from God and the imperfection of the best of our service we need His priestly office to reconcile us and present us to God as acceptable. Because of our antagonism and our utter inability to return to God, and because we need to be rescued and kept from spiritual enemies, we need His kingly office to convince, subdue, draw, sustain, deliver, and preserve us for His heavenly kingdom.
 John 8:58; Joe 2:32 with Romans 10:13; Psalm 102:25 with Hebrews 1:10; 1 Peter 2:3 with Psalm 34:8; Isaiah 8:12-13 with 3:15; John 1:1; 5:18; 20:28; Romans 9:5; Titus 2:13; Hebrews 1:8-9; Philippians 2:5-6; 2 Peter 1:1; 1 John 5:20
 Hebrews 10:5; Mark 14:8; Matthew 26:12,26; Luke 7:44-46; John 13:23; Matthew 9:10-13; 11:19; Luke 22:44; Hebrews 2:10; 5:8; 1 Peter 3:18; 4:1; John 19:32-35; Matthew 26:36-44; James 2:26; John 19:30; Luke 23:46; Matthew 26:39; 9:36; Mark 3:5; 10:14; John 11:35; Luke 19:41-44; 10:21; Matthew 4:1-11; Hebrews 4:15 with James 1:13; Luke 5:16; 6:12; 9:18,28; 2:40,52; Hebrews 5:8-9