It pleased God, in his eternal purpose, to choose and ordain the Lord Jesus, his only begotten son, in accordance with the covenant made between them both, to be the mediator between God and men; to be prophet, priest, and king, the head and savior of his church, the heir of all things, and the judge of all the world. To the Lord Jesus he gave, from all eternity, a people to be his seed. These, in time, would be redeemed, called, justified, sanctified, and glorified by the Lord Jesus.
The Son of God, the second person in the Holy Trinity, being true and eternal God, the brightness of the Father’s glory, of the same substance and equal with him; who made the world, and who upholds and governs all things which he has made, did, when the fullness of time had come, take upon himself man’s nature, with all its essential properties and common infirmities, with the exception of sin. He was conceived by the Holy Spirit in the womb of the Virgin Mary, the Holy Spirit coming down upon her and the power of the Most High overshadowing 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. Thus two whole, perfect and distinct natures were inseparably joined together in one person, without conversion, composition, or confusion; so that the Lord Jesus Christ is truly God and truly man, yet he is one Christ, the only mediator between God and men.
The Lord Jesus, his human nature thus once united to the divine in the person of the Son, was sanctified and anointed with the Holy Spirit above measure, having in himself all the treasures of wisdom and knowledge. It pleased the Father that all fullness should dwell in him so that, being holy, harmless [= innocent, free from guilt], undefiled, and full of grace and truth, he might be thoroughly furnished to execute the office of a mediator and surety, a position and duty which he did not take upon himself, but was called to perform by his Father. And the Father also put all power and judgment in his hand, and gave him commandment to exercise the same.
This office and duty of mediator and surety the Lord Jesus undertook most willingly. To discharge it, he was made under the law, and perfectly fulfilled it, and he underwent the punishment due to us, which we should have borne and suffered. He was made sin and was made a curse for us; enduring the most grievous sorrows in his soul with the most painful sufferings in his duty. He was crucified, and died, and remained in the state of the dead, but His body did not undergo any 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, and there sits at the right hand of his father making intercession, and shall return to judge men and angels at the end of the world.
The Lord Jesus, by his perfect obedience and sacrifice of himself which he, through the eternal Spirit, once offered up to God, has fully satisfied the justice of God, 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 paid by Christ until after his incarnation, yet the virtue, efficacy, and benefit arising from his payment were communicated to the elect in all ages from the beginning of the world through those promises, types, and sacrifices in which he was revealed and signified as the seed which should bruise the serpent’s head, and also the Lamb slain from the foundation of the world, for he is the same yesterday, and today, and forever.
Christ, in his work of mediation, acts according to both natures, each nature doing that which is proper to itself. Yet, because of the unity of his person, that which is proper to one nature is sometimes in Scripture attributed to the person denominated 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, uniting them to himself by his Spirit, revealing to them in the word and by the word the mystery of salvation. He persuades them to believe and obey, governing their hearts by his word and Spirit, and overcomes all their enemies by his almighty power and wisdom. This is achieved in such a manner and by such ways as are most consonant to his wonderful and unsearchable dispensation, and it is all by free and absolute grace, without any condition foreseen in them to procure it.
This office of mediator between God and man is proper only to Christ, who is the prophet, priest, and king of the church, and this office may not be transferred from him to any other, either in whole or in part.
This 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 aversion to, and utter inability to return to God, and for our rescue and keeping from spiritual enemies, we need his kingly office to convince, subdue, draw, uphold, deliver, and preserve us until we reach his heavenly kingdom.