A summary of ch. 5 of John Flavel’s The Fountain of Life.

“And the Word was made flesh, and dwelt among us.” John, 1:14

Here we have:

1. The Person assuming, the Word, that is, the second Person or Subsistent in the most glorious God-head; called the Word, either because he is the scope or principal matter, both of the prophetical and promissory word; or because he expounds and reveals the mind and will of God to men, as verse 18: “The only begotten Son, which is in the bosom of the Father, he hath declared” or expounded “him.”
2. The nature assumed.  The word flesh, rather than man, is doubtless used here to enhance the admirable condescension and abasement of Christ implying man’s vileness, weakness, and opposition to spirit.
3. The assumption itself, he was made.  He was made, that is, he took or assumed the true human nature into the unity of his Divine person, with all its integral parts and essential properties; and so was made, or became a true and real man, by that assumption. And when it is said, he was made flesh, misconceive not, as if there was a mutation of the Godhead into flesh; for this was performed, “not by changing what he was, but by assuming what he was not,” as Augustine well expresses it.  Heb 2:16.

This assertion “that the Word was made flesh,” is also here strongly confirmed. He “dwelt among us,” and we saw his glory.  1 Jn 1:1-3.

Hence,

Jesus Christ did really assume the true and perfect nature of man, into a personal union with his Divine nature, and still remains true God, and true man, in one person for ever.

The proposition contains one of the deepest mysteries of godliness, 1 Tim. 3:16. A mystery, by which apprehension is dazzled, invention astonished, and all expression swallowed up. The proper use of words is of great importance in this doctrine. We walk upon the brink of danger. The least tread awry may inguif us in the bogs of error. Arius would have been content, if the council of Nice would but have gratified him in a letter, [to have changed the meaning of the greek word for “of a like substance” for, “of the same substance] The Nestorians also desired but a letter, [one letter to be changed in the greek wording] These seemed but small and modest requests, but, if granted, had proved no small prejudice to the truth.  As Prosper has well said, “It is better not touch the bottom, than not keep within the circle.”

I. The nature of this union

1. The human nature was united to the Second Person miraculously and extraordinarily, being supernaturally framed in the womb of the virgin, by the overshadowing power of the Highest. Luke, 1:34, 35.
2. As it was produced miraculously, so it was assumed integrally.  He took a complete and perfect human soul and body.
3. He assumed our nature with all its sinless infirmities.  Heb 2:17; 4:15; Rom 8:3.
4. The human nature is so united with the Divine, as that each nature still retains its own essential properties distinct.

II. The effects, or immediate results of this marvelous union.

1. The two natures being thus united in the person of the Mediator, by virtue thereof the properties of each nature are attributed, and do truly agree in the whole person; so that it is proper to say, the Lord of glory was crucified, 1 Cor. 2:8, and the blood of God redeemed the church, Acts, 20:28, that Christ was both in heaven and in the earth at the same time, John, 3:13.
2. The singular advancement of the human nature in Christ, far beyond and above what it is capable of in any other person, Psa 45:7.
3. The concourse and cooperation of each nature in his mediatorial works; for in them he acts according to both natures: the human nature doing what is human, namely, suffering, sweating, bleeding, dying; and his Divine nature stamping all these with infinite value; and so both sweetly concur unto one glorious work and design of mediation.  2 Cor 5:10; Heb 9:14f.

III. The grounds and reasons of this assumption.

The Divine did not assume the human nature necessarily, but voluntarily; not out of indigence, but bounty; – not because it was to be perfected by it, but to perfect it, that so Christ might be prepared for the full discharge of his mediatorship, in the offices of our Prophet, Priest, and King.

Had he not possessed this double nature in the unity of his person, he could not have been our Prophet: for, as God, he knows the mind and will of God, John, 1:18, and 3:13; and as man he is fitted to impart it suitably to us, Deut. 18:15-18, compared with Acts, 20:22. As Priest, had he not been man, he could have shed no blood; and if not God, it had been of no adequate value for us, Heb. 2:17; Acts, 3:28. As King, had he not been man, he had been of a different nature, and so no fit head for us; and if not God, be could neither rule nor defend his body the church.

INFERENCES

1. Let all Christians rightly inform their minds in this truth of so great moment in religion, and hold it fast against all subtle adversaries that would wrest it from them. The learned Hooker observes, that the dividing of Christ’s person, which is but one, and the confounding of his natures, which are two, has been the occasion of. those errors which have so greatly disturbed the peace of the church. The Arians denied his Deity, leveling him with other created beings. The Apollinarians maimed his humanity. The Sabellians affirmed, that the Father and Holy Ghost were incarnated as well as the Son; and were forced upon that absurdity by another error, namely, denying the three distinct persons in the Godhead, and affirming they were but three names. The Eutychians confounded both natures in Christ, denying any distinction of them. The Seleusians affirmed that he unclothed himself of his humanity when he ascended, and has no human body in heaven. The Nestorians so rent the two names of Christ asunder, as to make two distinct persons of them.But ye, beloved, have not so learned Christ. Ye know he is,
   1. True and very God;
   2. True and very man; that,
   3. These two natures make but one person, being united inseparably;
   4. That they are not confounded or swallowed up one in another, but remain still distinct in the person of Christ.
2. Adore the love of the Father and the Son, who valued your souls so highly, and were willing to save you at such a cost.
3. And here infinite wisdom has also left a famous and everlasting mark of itself which invites, yea, even chains the eyes of angels and men to itself. Had there been a. general council of angels to devise a way of recovering poor sinners, they would all have been at an everlasting demur and loss about it.  Oh, bow wisely is the method of our recovery laid! so that Christ may be well called “the power and wisdom of God,” I Cor. 1:24; forasmuch as in him the Divine wisdom is more glorified than in all the other works of God upon which he has impressed it.
4. Hence also we infer the incomparable excellency of the Christian religion, that shows poor sinners such a sure foundation on which the trembling conscience may rest. While poor distressed souls look to themselves, they are perpetually in darkness. The cry of the distressed natural conscience is, “Wherewith shall I come before the Lord?” Conscience sees God arming himself with wrath, to avenge himself for sin, and cries out, Oh, how shall I prevent him; if he would accept the fruit of my body (those dear pledges of nature) for the sin of my soul, he should have them! But now we see God coming down in flesh, and so intimately uniting our nature to himself, that it had properly no personal separate subsistence, but is united with the Divine person: hence it is easy to imagine what worth and value must be in that blood; and how eternal love, springing forth triumphantly from it, flourishes into pardon, grace, and peace. Here is a way in which the sinner may see justice and mercy kissing each other, and the latter exercised freely without prejudice to the former. All other consciences, through the world, lie either in a deep sleep in the devil’s arms, or else are rolling, sea-sick, upon the waves of their own fears and dismal presages. Oh, happy are they that have dropped anchor on this ground, and not only know they have peace, but why they have it.
5. Of how great moment is it, that Christ should have union with our particular persons, as well as with our common nature!  Thy sin is thereby aggravated beyond the sin of devils, who never sinned against a mediator in their own nature; who never despised, or refused, because, indeed, they were never offered terms of mercy, as you are.
6. If Jesus Christ has assumed our nature, then he is sensibly touched with the infirmities that attend it, and so hath pity and compassion for us under all our burdens. And indeed this was one end of his assuming it, that he might be able to have compassion on us.
7. Hence we see to what a height God intends to build up the happiness of man, in that he hath laid the foundation thereof so deep, in the incarnation of his Son.
8. How wonderful a comfort is it, that he who dwells in our flesh is God! What joy may not a poor believer make out of this! God and man in one person! Oh! thrice happy conjunction! As man, he is full of experimental sense of our infirmities, wants, and burdens; and, as God, he can support and supply them all.