Of the Two Natures in Christ
The article of the incarnation, or of the two natures in Christ, and their hypostatical union is next to be considered. The questions which are here to be expounded somewhat largely, are the following:
I. Are there two natures in the Mediator?
II. Do these natures constitute one or two persons?
III. If but one person, what is the nature of this union?
IV. Why was it necessary that the hypostatical union should be constituted?

I. Are there two natures in the Mediator?
That Christ has a divine nature has already been proven. That he has a human nature was formerly denied by Marcion, and is to this day denied by the Swenckfieldians, who hold that Christ is a man only in name. It is, therefore, to be proven against heretics, that Christ is a true and natural man, consisting of a body and soul, perfectly and truly, and subject to all infirmities, sin excepted. The proofs of this are:

1. The testimonies of Scripture, which teach that Christ had all the parts of human nature, and that he was made like unto us in all things, sin only excepted. “For both he that sanctifieth and they who are sanctified, are all of one; for which cause he is not ashamed to call them brethren. Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same. For verily he took not on him the nature of angels; but he took on him the seed of Abraham. Wherefore, in all things it behooved him to be made like unto his brethren, that he might be a merciful and faithful High Priest in things pertaining to God, to make reconciliation for the sins of the people.” “For we have not an High Priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.” (Heb. 2:11-18, & 4:15.) Those passages of Scripture are here likewise in point, in which our Lord himself confirmed the truth of his human nature after his resurrection, as when he said to the disciples, “Handle me and see; for a spirit hath not flesh and bones as ye see me have,” &c. (Luke 24:39, 40.)

There have been those who have maintained that the Divinity of Christ was constituted the soul of his body. Thus Appollinarius taught, that Christ had indeed a true human nature, but that the Word was united to him in the place of a soul. This heresy is easily refuted by the words of Christ himself, “ My soul is exceeding sorrowful, even unto death.” (Matt. 27:38.) The body now cannot be said to be sorrowful, for it is not susceptible of grief; neither can sadness be attributed to the Divinity, for this is free from every passion. “Father, into thy hands I commend my spirit, and having thus said he gave up the ghost.” (Luke 23:46.) The spirit here signifies the soul, and not the Divinity, because the Divinity never departed from the human nature. And, again, it is said by Paul, Heb. 2:17, “It behooved him to be made like unto his brethren.” But without a soul he would not have been like unto his brethren in all things; for he would not have been a true man. Hence it must needs be that Christ had a human soul.

2. The same doctrine is also confirmed by the divine promises and prophecies; for the Messiah was promised to be such an one as would be the seed of the woman, the seed of Abraham, the son of David, the son of a Virgin, &c. “ The seed of the woman shall bruise the serpent's head.” “Behold a Virgin shall conceive and bear a son.” “The book of the generation of Jesus Christ, the son of David, the son of Abraham.” “Blessed is the fruit of thy womb.” “Concerning his Son Jesus Christ, who was made of the seed of David according to the flesh.” (Gen. 8:15. Is. 7:14. Matt. 1:1. Luke 1:42. Rom. 1:3.) The argument which is drawn from these declarations made in relation to the Messiah, is most convincing; for if the humanity which he assumed was from the seed of Abraham, and of David, then he had a real human nature.

3. The office of mediator demanded in Christ, our deliverer, a true human nature taken from ours, which had sinned, and which was to be redeemed through him, as we have shown in the former part of this work; for it behooved the same nature which had sinned, to suffer and make satisfaction for sin. Therefore, inasmuch as our nature sinned, Christ took this upon himself, and not a nature created out of nothing, or brought down from heaven, &c. Nor did it merely behoove our mediator to take upon him our nature, but it was further necessary that he should retain and keep it for ever; because the Father receives us into his favor only upon the condition that we remain engrafted into his Son. This consolation, too, that Christ is our brother, that he bears our nature, and is bone of our bone, and flesh of our flesh, is necessary for us continually, even in eternity; for we should lose this consolation if Christ had not truly taken our nature, and would not retain it forever. Without this he would not be our brother.

Obj. 1. The flesh of Adam (that is, that which is made over to his posterity by generation) is sinful. But the flesh of Christ is not sinful. Therefore it is not of the flesh of Adam. Ans. There is here a fallacy of accident, in affirming that to be true of the substance which is true only by an accident. Since the flesh of Adam is not sinful in itself, but only by an accident, it also follows that the flesh of Christ is, only in respect to that accident, not the flesh of Adam, but is, according to the substance, the same flesh of Adam. Hence the argument ought rather to be changed thus: The flesh of Adam is true flesh. The flesh of Christ is the flesh of Adam, Therefore the flesh of Christ is true flesh.

Obj. 2. Christ was conceived by the Holy Ghost. Therefore his flesh was produced and propagated from the substance of the Holy Ghost, and is for this reason no creature. Ans. We reply to this as we did to the objection brought forward under the thirty-fifth Question of the Catechism, that there is a fallacy in misunderstanding the figure of speech that is employed; inasmuch as the particle by does not signify a material, but an efficient cause.

Obj. 3. In God there are not two natures. Christ is God. Therefore there are not two natures in Christ. Ans. Nothing can be established by mere particulars: for the major does not express what is universally true; but what is true only of God, the Father, and Holy Ghost, and not of the incarnate Son, which is God manifested in the flesh.

Reply 1. But nothing can be added unto God by reason of his perfection. The Son is God. Therefore it is not possible to add human nature to his Divinity. Ans. We grant that nothing can be added to God by way of perfection, so as to change or perfect his essence; but there may be something added to him by copulation, or union; because he took upon him the seed of Abraham.

Reply. 2. God dwells in light inaccessible. Therefore it is not possible that human nature could ever approach him. Ans. It is conceded that human, nature cannot approach God, much less become personally united to him, unless he draw, assume, and unite it with himself.

Reply 3. It is reproachful to God to be a creature. Ans. It would, indeed, be reproachful to God if he were to be changed into a creature; but that he should be united with a created nature, without a change of his own essence, is honorable unto God, as he, by this means, demonstrates to the whole world, his infinite wisdom, goodness and power.