And the angel answered and said to her, "The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born will be called the Son of God. Luke 1:35NKJV
Question 47 of the Larger Catechism, asks, “How did Christ humble himself in his conception and birth?” It gives the answer, “Christ humbled himself in his conception and birth, in that, being from all eternity the Son of God, in the bosom of the Father, he was pleased in the fulness of time to become the son of man, made of a woman of low estate, and to be born of her; with divers circumstances of more than ordinary abasement.” Last week we looked at Christ’s lowly and poor birth family and how He shared their condition. Today we consider the humility of the incarnation itself.
From all eternity Jesus Christ is the second Person of the Triune God. He was, is, and will always be fully God, the same in substance and equal in all glory and power with the Father and the Spirit. So when Jesus agreed to take upon Himself a human nature He agreed to be united to a being that was infinitely below Him. Though He is infinite and omnipresent, yet in a very real way God the Son dwelt for nine months in the physical womb of a human being. The nature that He united to was composed of her created substance. He took her DNA, her flesh and her bones, and grew through the entire gestation period as any ordinary human being would. When the time was right He was birthed in all of the blood, pain, and fluids of all human births. Then for many months as a helpless babe, He had to be fed, changed, bathed, dressed, and cared for. And as a child He would have to learn to walk, speak, read, and write. In everything He would have to learn as all of us learn, laboring through repetition, memory, and imitation.
Though His divine nature would remain fully God throughout His conception, birth, and earthly life, His human nature had to be fully human. The person Jesus would get tired. He would know hunger and thirst. He would not be all-powerful, all-knowing, or everywhere at once. And He could and actually would die. Now we rightly ascribe all of these limitations and weaknesses to His human nature, for in His divine nature, throughout His incarnation, Jesus could not get tired, hungry, or thirsty. He was always all-powerful, all-knowing, and everywhere present. And it was not possible for Him to die. Yet this divine nature remained fully united to a human nature that had all of these limitations throughout His earthly life in the one person of the Lord Jesus Christ, the God-man.
Not only did Christ in His human nature have these creaturely limitations, but Scripture makes it clear that Jesus, though sinless, took upon Himself a nature that was subject to all of the other curses of the Fall. Thus, Jesus’ human nature was not in the likeness of glorified humanity but “in the likeness of sinful flesh,” (Rom. 8:3). Unlike pre-fallen Adam, Jesus would have known the weakness, sickness, and mortality that all fallen humans experience. The thorns, thistles, sweat, and labor of the curse would afflict Him who was not under the curse, for this is what He had to endure in order to free us from these things. His flesh was not sinful, but He came in the likeness of sinful flesh. Such were the humiliations of the job description of becoming the second Adam, for His mission was not to save an unfallen race, but a fallen one and so the humanity that He took up was a humanity not only lowly in its creatureliness but in its fallenness.
Finally, we should notice that when Jesus willingly took upon Himself a human nature He did it for all time. His human nature must be a true human nature, and true human natures exist forever either in Heaven or in Hell. Therefore, Jesus Christ will always have His divine nature fully united to His human nature in one person forever and ever. His human nature is now glorified and no longer subject to the curse of the Fall, even as we will one day be. But forevermore, the second Person of the Trinity will be the God-man. All this He did for us.