Who is the Mediator of the covenant of grace?
The only Mediator of the covenant of grace is the Lord Jesus Christ,1 who, being the eternal Son of God, of one substance and equal with the Father,2 in the fulness of time became man,3 and so was and continues to be God and man, in two entire distinct natures, and one person, forever.4
Scripture proofs
The Westminster Assembly's proof texts (KJV). The bracketed numbers in the answer above mark the clause each set of references supports; expand a row to read the verses.
1 1 Tim. 2:5
For there is one God, and one mediator between God and men, the man Christ Jesus;
2 John 1:1, 14; John 10:30; Phil. 2:6
John 1:1 In the beginning was the Word, and the Word was with God, and the Word was God.
John 1:14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
I and my Father are one.
Who, being in the form of God, thought it not robbery to be equal with God:
3 Gal. 4:4
But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law,
4 Luke 1:35; Rom. 9:5; Col. 2:9; Heb. 7:24–25
And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen.
For in him dwelleth all the fulness of the Godhead bodily.
Heb. 7:24 But this man, because he continueth ever, hath an unchangeable priesthood.
Heb. 7:25 Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.
This doctrine across the Standards
Where the Confession and the Westminster Shorter Catechism treat the same matter, so the question can be studied alongside its parallel statements.
In the Westminster Confession
VIII.2 The Son of God, the second person in the Trinity, being very and eternal God, of one substance, …
The Son of God, the second person in the Trinity, being very and eternal God, of one substance, and equal with the Father, did, when the fulness of time was come, take upon him man's nature, with all the essential properties and common infirmities thereof, yet without sin: being conceived by the power of the Holy Ghost in the womb of the Virgin Mary, of her substance. So that two whole, perfect, and distinct natures, the Godhead and the manhood, were inseparably joined together in one person, without conversion, composition, or confusion. Which person is very God and very man, yet one Christ, the only mediator between God and man.
→ VIII.2 · Of Christ the MediatorVIII.3 The Lord Jesus, in his human nature thus united to the divine, was sanctified and anointed with the …
The Lord Jesus, in his human nature thus united to the divine, was sanctified and anointed with the Holy Spirit above measure; having in him all the treasures of wisdom and knowledge, in whom it pleased the Father that all fulness should dwell; to the end that, being holy, harmless, undefiled, and full of grace and truth, he might be thoroughly furnished to execute the office of a mediator and surety. Which office he took not unto himself, but was thereunto called by his Father, who put all power and judgment into his hand, and gave him commandment to execute the same.
→ VIII.3 · Of Christ the MediatorIn the Westminster Shorter Catechism
Q.21 Who is the Redeemer of God's elect?
The only Redeemer of God's elect is the Lord Jesus Christ, who, being the eternal Son of God, became man and so was, and continueth to be, God and man in two distinct natures, and one person, forever.
→ Open Q.21Q.22 How did Christ, being the Son of God, become man?
Christ, the Son of God, became man, by taking to himself a true body, and a reasonable soul, being conceived by the power of the Holy Ghost, in the womb of the virgin Mary, and born of her yet without sin.
→ Open Q.22