the geneva catechism 4
begotten of the substance of His Father, and is of one essence with Him, is rightly called the only Son of God (John 1:14; Heb. 1:2) for there is no other who is God's Son by nature.
47. You mean to say, then, that this honour is proper to Him alone, and belongs to Him by nature, but is communicated to us through a gracious gift, in that we are His numbers. That is so. Hence in regard to this communication He is called elsewhere "the First-born among many brethren" (Rom. 8:29; Col. 1:15).
48. How is He "our Lord"? Because He is appointed by the Father to have us under His government, to administer the Kingdom and the Lordship of God in heaven and on earth, and to be the Head of men and believers (Eph. 5:23; Col. 1:18).
49. What is meant by what follows? It declares how the Son of God was anointed by the Father to be our Saviour. That is to say, He assumed human flesh, and accomplished all things necessary to our salvation, as enunciated here.
50. What do you mean by the two clauses, "Conceived of the Holy Ghost, born of the Virgin Mary"? That He was formed in womb of the Virgin Mary, of her proper substance, to be the seed of David, as had been foretold (Ps. 132:11), and yet that this was wrought by the miraculous operation of the Holy Spirit, without the cooperation of a man (Matt. 1:18; Luke 1:35).
51. Was it then required that He should put on our very flesh? Yes, because it was necessary that the disobedience committed by man against God should be redressed in human nature. And moreover He could not otherwise be our Mediator to reconcile us to God His Father (1 Tim. 2:5; Heb. 4:15).
52. You say that Christ had to become man, to fulfill the office of Saviour, as in our very person. Yes, indeed. For we must recover in Him all that we lack in ourselves, and this cannot be done in any other way.