The nature of the hypostatic union — God and man

Christ could not be described as being man without flesh, nor the Son of man without any human parent; just as He is not God without the Spirit of God, nor the Son of God without having God for His father. Thus the nature of the two substances displayed Him as man and God,—in one respect born, in the other unborn; in one respect fleshly, in the other spiritual; in one sense weak, in the other exceeding strong; in one sense dying, in the other living. This property of the two states—the divine and the human—is distinctly asserted with equal truth of both natures alike, with the same belief both in respect of the Spirit and of the flesh. The powers of the Spirit, proved Him to be God, His sufferings attested the flesh of man.

Tertullian
On the Flesh of Christ
Chapter V

Was God not really crucified?

But answer me at once, you that murder truth:  Was not God really crucified?  And, having been really crucified, did He not really die? And, having indeed really died, did He not really rise again?

…O thou most infamous of men, who acquittest of all guilt the murderers of God!

Tertullian
On the Flesh of Christ
Chapter V

The Incarnation is foolishness to man

But, Marcion, consider well this Scripture, if indeed you have not erased it: “God hath chosen the foolish things of the world, to confound the wise.” Now what are those foolish things? Are they the conversion of men to the worship of the true God, the rejection of error, the whole training in righteousness, chastity, mercy, patience, and innocence?  These things certainly are not “foolish.” Inquire again, then, of what things he spoke, and when you imagine that you have discovered what they are will you find anything to be so “foolish” as believing in a God that has been born, and that of a virgin, and of a fleshly nature too, who wallowed in all the before-mentioned humiliations of nature?  But some one may say, “These are not the foolish things; they must be other things which God has chosen to confound the wisdom of the world.” And yet, according to the world’s wisdom, it is more easy to believe that Jupiter became a bull or a swan, if we listen to Marcion, than that Christ really became a man.

Tertullian
On the Flesh of Christ
Chapter IV

If angels could become men in the scriptures and remain angels, then why couldn’t Christ become man and remain God?

You have sometimes read and believed that the Creator’s angels have been changed into human form, and have even borne about so veritable a body, that Abraham even washed their feet, and Lot was rescued from the Sodomites by their hands; an angel, moreover, wrestled with a man so strenuously with his body, that the latter desired to be let loose, so tightly was he held. Has it, then, been permitted to angels, which are inferior to God, after they have been changed into human bodily form, nevertheless to remain angels? and will you deprive God, their superior, of this faculty, as if Christ could not continue to be God, after His real assumption of the nature of man? Or else, did those angels appear as phantoms of flesh? You will not, however, have the courage to say this; for if it be so held in your belief, that the Creator’s angels are in the same condition as Christ, then Christ will belong to the same God as those angels do, who are like Christ in their condition. If you had not purposely rejected in some instances, and corrupted in others, the Scriptures which are opposed to your opinion…

 

Tertullian 
On the Flesh of Christ
Chapter III

Christ did not cease to be God when he became man

Why, I want to know, was it of so much importance, that Christ should, when perfectly aware what He really was, exhibit Himself as being that which He was not? You cannot express any apprehension that, if He had been born and truly clothed Himself with man’s nature, He would have ceased to be God, losing what He was, while becoming what He was not. For God is in no danger of losing His own state and condition.

Tertullian 
On the Flesh of Christ
Chapter III

God willed to be born in the likeness of man

Since you think that this lay within the competency of your own arbitrary choice, you must needs have supposed that being born was either impossible for God, or unbecoming to Him. With God, however, nothing is impossible but what He does not will. Let us consider, then, whether He willed to be born (for if He had the will, He also had the power, and was born). I put the argument very briefly. If God had willed not to be born, it matters not why, He would not have presented Himself in the likeness of man.

Tertullian
On the Flesh of Christ
Chapter III

The Holy Spirit created all things and the Scriptures are His

And to such a degree has the Holy Ghost made this the rule of His Scripture, that whenever anything is made out of anything, He mentions both the thing that is made and the thing of which it is made. “Let the earth,” says He, “bring forth grass, the herb yielding seed, and the fruit-tree yielding fruit after its kind, whose seed is in itself, after its kind.

…if the Holy Ghost took upon Himself so great a concern for our instruction, that we might know from what everything was produced, would He not in like manner have kept us well informed about both the heaven and the earth, by indicating to us what it was that He made them of, if their original consisted of any material substance, so that the more He seemed to have made them of nothing, the less in fact was there as yet made, from which He could appear to have made them?

Tertullian
Against Hermogenes
Chapter XXII

The Logos is begotten from within God, not outside of him

Indeed, as soon as He perceived It to be necessary for His creation of the world, He immediately creates It, and generates It in Himself. “The Lord,” says the Scripture, “possessed me, the beginning of His ways for the creation of His works. Before the worlds He founded me; before He made the earth, before the mountains were settled in their places; moreover, before the hills He generated me, and prior to the depths was I begotten.” Let Hermogenes then confess that the very Wisdom of God is declared to be born and created, for the especial reason that we should not suppose that there is any other being than God alone who is unbegotten and uncreated. For if that, which from its being inherent in the Lord was of Him and in Him, was yet not without a beginning,—I mean His wisdom, which was then born and created, when in the thought of God It began to assume motion for the arrangement of His creative works,—how much more impossible is it that anything should have been without a beginning which was extrinsic to the Lord!

Tertullian
Against Hermogenes
Chapter XVIII

Hermogenes denies Christ created all things out of nothing

He is a thorough adulterer, both doctrinally and carnally, since he is rank indeed with the contagion of your marriage-hacks, and has also failed in cleaving to the rule of faith as much as the apostle’s own Hermogenes. However, never mind the man, when it is his doctrine which I question. He does not appear to acknowledge any other Christ as Lord, though he holds Him in a different way; but by this difference in his faith he really makes Him another being,—nay, he takes from Him everything which is God, since he will not have it that He made all things of nothing.

Tertullian
Against Hermogenes
Chapter I