"Why the Incarnation?" Calvin's Explanation

The situation would surely have been hopeless had the very majesty of God not descended to us, since it was not in our power to ascend to him. Hence, it was necessary for the Son of God to become for us “Immanuel, that is, God with us” [Isa. 7:14; Matt. 1:23], and in such a way that his divinity and our human nature might by mutual connection grow together. Otherwise the nearness would not have been near enough, nor the affinity sufficiently firm, for us to hope that God might dwell with us. So great was the disagreement between our uncleanness and God’s perfect purity! Even if man had remained free from all stain, his condition would have been too lowly for him to reach God without a Mediator. What, then, of man: plunged by his mortal ruin into death and hell, defiled with so many spots, befouled with his own corruption, and overwhelmed with every curse? In undertaking to describe the Mediator, Paul then, with good reason, distinctly reminds us that He is man: “One mediator between God and men, the man Jesus Christ” [1 Tim. 2:5]. He could have said “God”; or he could at least have omitted the word “man” just as he did the word “God.” But because the Spirit speaking through his mouth knew our weakness, at the right moment he used a most appropriate remedy to meet it: he set the Son of God familiarly among us as one of ourselves. Therefore, lest anyone be troubled about where to seek the Mediator, or by what path we must come to him, the Spirit calls him “man,” thus teaching us that he is near us, indeed touches us, since he is our flesh. Here he surely means the same thing that is explained elsewhere at greater length: “We have not a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sinning” [Heb. 4:15].

John Calvin, Institutes, II.12.1