Q. Who is the Mediator of the covenant of grace?
A. The only Mediator of the covenant of grace is the Lord Jesus Christ, who, being the eternal Son of God, of one substance and equal with the Father, in the fulness of time became man, and so was and continues to be God and man, in two entire distinct natures, and one person, forever.
Q. How did Christ, being the Son of God, become man?
A. 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, of her substance, and born of her, yet without sin.
Q. Why was it requisite that the Mediator should be God?
A. It was requisite that the Mediator should be God, that he might sustain and keep the human nature from sinking under the infinite wrath of God, and the power of death, give worth and efficacy to his sufferings, obedience, and intercession; and to satisfy God’s justice, procure his favour, purchase a peculiar people, give his Spirit to them, conquer all their enemies, and bring them to everlasting salvation.
Q. Why was it requisite that the Mediator should be man?
A. It was requisite that the Mediator should be man, that he might advance our nature, perform obedience to the law, suffer and make intercession for us in our nature, have a fellow-feeling of our infirmities; that we might receive the adoption of sons, and have comfort and access with boldness unto the throne of grace.
Q. Why was it requisite that the Mediator should be God and man in one person?
A. It was requisite that the Mediator, who was to reconcile God and man, should himself be both God and man, and this in one person, that the proper works of each nature might be accepted of God for us, and relied on by us as the works of the whole person.
Q. Why was our Mediator called Jesus?
A. Our Mediator was called Jesus, because he saveth his people from their sins.
(Questions XXXVI, XXXVII, XXXVIII, XXXIX, XL and XLI of the Westminster Larger Catechism.)