He declined not to take what was peculiar to us, that he might in his turn extend to us what was peculiarly his own, and thus might be in common with us both Son of God and Son of man. Hence that holy brotherhood which he commends with his own lips, when he says, “I ascend to my Father, and your Father, to my God, and your God,” (John 20:17). In this way, we have a sure inheritance in the heavenly kingdom, because the only Son of God, to whom it entirely belonged, has adopted us as his brethren; and if brethren, then partners with him in the inheritance (Rom. 8:17). Moreover, it was especially necessary for this cause also that he who was to be our Redeemer should be truly God and man. It was his to swallow up death: who but Life could do so? It was his to conquer sin: who could do so save Righteousness itself? It was his to put to flight the powers of the air and the world: who could do so but the mighty power superior to both? But who possesses life and righteousness, and the dominion and government of heaven, but God alone? Therefore, God, in his infinite mercy, having determined to redeem us, became himself our Redeemer in the person of his only begotten Son.
John Calvin, Institutes of the Christian Religion, 2.12.2.