The heresies of Blastus, Theodotus and Praxeas

…there is likewise Blastus, who would latently introduce Judaism. For he says the passover is not to be kept otherwise than according to the law of Moses, on the fourteenth of the month. But who would fail to see that evangelical grace is escheated if he recalls Christ to the Law?

Add to these Theodotus the Byzantine, who, after being apprehended for Christ’s Name, and apostatizing, ceased not to blaspheme against Christ.  For he introduced a doctrine by which to affirm that Christ was merely a human being, but deny His deity; teaching that He was born of the Holy Spirit indeed of a virgin, but was a solitary and bare human being, with no pre-eminence above the rest (of mankind), but only that of righteousness.

…After him brake out a second heretical Theodotus, who again himself introduced a sister-sect, and says that the human being Christ Himself was merely conceived alike, and born, of the Holy Spirit and the Virgin Mary, but that He was inferior to Melchizedek;

…But after all these, again, one Praxeas introduced a heresy which Victorinus was careful to corroborate. He asserts that Jesus Christ is God the Father Almighty.  Him he contends to have been crucified, and suffered, and died;

Tertullian
Against All Heresies
Chapter VIII

John 1:1 can only be interpreted to mean one thing — Christ is God but distinct from the Father

…first of all there comes at once to hand the preamble of John to his Gospel, which shows us what He previously was who had to become flesh.  “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God: all things were made by Him, and without Him was nothing made.” Now, since these words may not be taken otherwise than as they are written, there is without doubt shown to be One who was from the beginning, and also One with whom He always was: one the Word of God, the other God (although the Word is also God, but God regarded as the Son of God, not as the Father); One through whom were all things, Another by whom were all things.  But in what sense we call Him Another we have already often described. In that we called Him Another, we must needs imply that He is not identical—not identical indeed, yet not as if separate; Other by dispensation, not by division.

Tertullian
Against Praxeas
Chapter XXI

Praxeas’ heresy mistakenly uses a few passages against a great many

For, inasmuch as only a few testimonies are to be found (making for them) in the general mass, they pertinaciously set off the few against the many, and assume the later against the earlier. The rule, however, which has been from the beginning established for every case, gives its prescription against the later assumptions, as indeed it also does against the fewer.

Tertullian
Against Praxeas
Chapter XX

Heretics spiritualize everything, even death

For some, when they have alighted on a very usual form of prophetic statement, generally expressed in figure and allegory, though not always, distort into some imaginary sense even the most clearly described doctrine of the resurrection of the dead, alleging that even death itself must be understood in a spiritual sense.

Tertullian
On the Resurrection of the Flesh
Chapter XIX

The Marcionites believe in a resurrection of the soul only

Since there is even within the confines of God’s Church a sect which is more nearly allied to the Epicureans than to the prophets, an opportunity is afforded us of knowing what estimate Christ forms of the (said sect, even the) Sadducees. For to Christ was it reserved to lay bare everything which before was concealed:  to impart certainty to doubtful points; to accomplish those of which men had had but a foretaste; to give present reality to the objects of prophecy; and to furnish not only by Himself, but actually in Himself, certain proofs of the resurrection of the dead. It is, however, against other Sadducees that we have now to prepare ourselves, but still partakers of their doctrine. For instance, they allow a moiety of the resurrection; that is, simply of the soul, despising the flesh, just as they also do the Lord of the flesh Himself.  No other persons, indeed, refuse to concede to the substance of the body its recovery from death, heretical inventors of a second deity.

Tertullian
On the Resurrection of the Flesh
Chapter II

Heretics use the Scriptures to try and deny that God was actually born of a woman

But whenever a dispute arises about the nativity, all who reject it as creating a presumption in favour of the reality of Christ’s flesh, wilfully deny that God Himself was born, on the ground that He asked, “Who is my mother, and who are my brethren?”

Tertullian
On the Flesh of Christ
Chapter VII

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

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