Westminster Larger Catechism (Q31-40)

Q31: With whom was the covenant of grace made?
A: The covenant of grace was made with Christ as the second Adam, and in him with all the elect as his seed.

Q32: How is the grace of God manifested in the second covenant?
A: The grace of God is manifested in the second covenant, in that he freely provides and offers to sinners a Mediator, and life and salvation by him; and requiring faith as the condition to interest them in him, promises and gives his Holy Spirit to all his elect, to work in them that faith, with all other saving graces; and to enable them unto all holy obedience, as the evidence of the truth of their faith and thankfulness to God, and as the way which he has appointed them to salvation.

Q33: Was the covenant of grace always administered after one and the same manner?
A: The covenant of grace was not always administered after the same manner, but the administrations of it under the Old Testament were different from those under the New.

Q34: How was the covenant of grace administered under the Old Testament?
A: The covenant of grace was administered under the Old Testament, by promises, prophecies, sacrifices, circumcision, the passover, and other types and ordinances, which did all foresignify Christ then to come, and were for that time sufficient to build up the elect in faith in the promised Messiah, by whom they then had full remission of sin, and eternal salvation.

Q35: How is the covenant of grace administered under the New Testament?
A: Under the New Testament, when Christ the substance was exhibited, the same covenant of grace was and still is to be administered in the preaching of the Word, and the administration of the sacraments of Baptism and the Lord's Supper; in which grace and salvation are held forth in more fulness, evidence, and efficacy, to all nations.

Q36: 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.

Q37: 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.

Q38: 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 favor, purchase a peculiar people, give his Spirit to them, conquer all their enemies, and bring them to everlasting salvation.

Q39: 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.

Q40: 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.