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

Some of the Gnostics teach that God the Father is also a man

Some there are who have imagined that another origin must be found for the title “Son of man;” for they have had the presumption to call the Father Himself Man, by reason of the profound mystery of this title: so that what can you hope for more ample concerning faith in that God, with whom you are now yourself on a par? Such conceits are constantly cropping out amongst them, from the redundance of their mother’s seed. And so it happens that the doctrines which have grown up amongst the Valentinians have already extended their rank growth to the woods of the Gnostics.

Tertullian
Against the Valentinians
Chapter XXXIX

Some heresies are so ridiculous they just make you laugh

There are many things which deserve refutation in such a way as to have no gravity expended on them. Vain and silly topics are met with especial fitness by laughter. Even the truth may indulge in ridicule, because it is jubilant; it may play with its enemies, because it is fearless. Only we must take care that its laughter be not unseemly, and so itself be laughed at; but wherever its mirth is decent, there it is a duty to indulge it.

Tertullian
Against the Valentinians
Chapter VI

Valentinus left the church before inventing his heresy

Valentinus had expected to become a bishop, because he was an able man both in genius and eloquence. Being indignant, however, that another obtained the dignity by reason of a claim which confessorship had given him, he broke with the church of the true faith. Just like those (restless) spirits which, when roused by ambition, are usually inflamed with the desire of revenge, he applied himself with all his might to exterminate the truth; and finding the clue of a certain old opinion, he marked out a path for himself with the subtlety of a serpent. Ptolemæus afterwards entered on the same path, by distinguishing the names and the numbers of the Ænons into personal substances, which, however, he kept apart from God. Valentinus had included these in the very essence of the Deity, as senses and affections of motion. Sundry bypaths were then struck off therefrom, by Heraclean and Secundus and the magician Marcus. Theotimus worked hard about “the images of the law.” Valentinus, however, was as yet nowhere, and still the Valentinians derive their name from Valentinus. Axionicus at Antioch is the only man who at the present time does honour to the memory of Valentinus, by keeping his rules to the full. But this heresy is permitted to fashion itself into as many various shapes as a courtezan, who usually changes and adjusts her dress every day. And why not?  When they review that spiritual seed of theirs in every man after this fashion, whenever they have hit upon any novelty, they forthwith call their presumption a revelation, their own perverse ingenuity a spiritual gift; but (they deny all) unity, admitting only diversity.

Tertullian
Against the Valentinians
Chapter IV

Matter had no prior existence

Therefore, in as far as it has become evident that Matter had no prior existence (even from this circumstance, that it is impossible for it to have had such an existence as is assigned to it), in so far is it proved that all things were made by God out of nothing. It must be admitted, however, that Hermogenes, by describing for Matter a condition like his own—irregular, confused, turbulent, of a doubtful and precipate and fervid impulse—has displayed a specimen of his own art, and painted his own portrait.

Tertullian
Against Hermogenes
Chapter XLV

Hermogenes has a low view of matter

Does that which is good never desire, never wish, never feel able to advance, so as to change its good for a better? And in like manner, if Matter had been by nature evil, why might it not have been changed by God as the more powerful Being, as able to convert the nature of stones into children of Abraham? Surely by such means you not only compare the Lord with Matter, but you even put Him below it, since you affirm that the nature of Matter could not possibly be brought under control by Him, and trained to something better.

Tertullian
Against Hermogenes
Chapter XXXVII

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