Heresies can’t prove their connection to the Apostolic faith

Let the entire mass of heresies choose, therefore, for themselves the times when they should appear, provided that the when be an unimportant point; allowing, too, that they be not of the truth, and (as a matter of course) that such as had no existence in the time of the apostles could not possibly have had any connection with the apostles. If indeed they had then existed, their names would be extant, with a view to their own repression likewise.  Those (heresies) indeed which did exist in the days of the apostles, are condemned in their very mention. If it be true, then, that those heresies, which in the apostolic times were in a rude form, are now found to be the same, only in a much more polished shape, they derive their condemnation from this very circumstance. Or if they were not the same, but arose afterwards in a different form, and merely assumed from them certain tenets, then, by sharing with them an agreement in their teaching, they must needs partake in their condemnation, by reason of the above-mentioned definition, of lateness of date, which meets us on the very threshold. Even if they were free from any participation in condemned doctrine, they would stand already judged on the mere ground of time, being all the more spurious because they were not even named by the apostles. Whence we have the firmer assurance, that these were (the heresies) which even then, were announced as about to arise.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXXIV

If the heretic’s faith is true, let him prove it by a record of Apostolic succession and full-communion status

But if there be any (heresies) which are bold enough to plant themselves in the midst of the apostolic age, that they may thereby seem to have been handed down by the apostles, because they existed in the time of the apostles, we can say: Let them produce the original records of their churches; let them unfold the roll of their bishops, running down in due succession from the beginning in such a manner that [that first bishop of theirs] bishop shall be able to show for his ordainer and predecessor some one of the apostles or of apostolic men,—a man, moreover, who continued stedfast with the apostles. For this is the manner in which the apostolic churches transmit their registers: as the church of Smyrna, which records that Polycarp was placed therein by John; as also the church of Rome, which makes Clement to have been ordained in like manner by Peter. In exactly the same way the other churches likewise exhibit (their several worthies), whom, as having been appointed to their episcopal places by apostles, they regard as transmitters of the apostolic seed. Let the heretics contrive something of the same kind.

….To this test, therefore will they be submitted for proof by those churches, who, although they derive not their founder from apostles or apostolic men (as being of much later date, for they are in fact being founded daily), yet, since they agree in the same faith, they are accounted as not less apostolic because they are akin in doctrine. Then let all the heresies, when challenged to these two tests by our apostolic church, offer their proof of how they deem themselves to be apostolic. But in truth they neither are so, nor are they able to prove themselves to be what they are not. Nor are they admitted to peaceful relations and communion by such churches as are in any way connected with apostles, inasmuch as they are in no sense themselves apostolic because of their diversity as to the mysteries of the faith.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXXII

Only the faith first delivered is truth. Everything that has come after is false.

Let me return, however, from this digression to discuss the priority of truth, and the comparative lateness of falsehood, deriving support for my argument even from that parable which puts in the first place the sowing by the Lord of the good seed of the wheat, but introduces at a later stage the adulteration of the crop by its enemy the devil with the useless weed of the wild oats.  For herein is figuratively described the difference of doctrines, since in other passages also the word of God is likened unto seed. From the actual order, therefore, it becomes clear, that that which was first delivered is of the Lord and is true, whilst that is strange and false which was afterwards introduced. This sentence will keep its ground in opposition to all later heresies, which have no consistent quality of kindred knowledge inherent in them—to claim the truth as on their side.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXXI

Preaching a new gospel would require Christ to come a second time; and that’s impossible before the end

There is, however, a certain man named Nigidius, and Hermogenes, and several others, who still pursue the course of perverting the ways of the Lord. Let them show me by what authority they come!  If it be some other God they preach, how comes it that they employ the things and the writings and the names of that God against whom they preach? If it be the same God, why treat Him in some other way? Let them prove themselves to be new apostles! Let them maintain that Christ has come down a second time, taught in person a second time, has been twice crucified, twice dead, twice raised! For thus has the apostle described (the order of events in the life of Christ); for thus, too, is He accustomed to make His apostles—to give them, (that is), power besides of working the same miracles which He worked Himself.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXX

A restoration of the true Church is impossible

In whatever manner error came, it reigned of course only as long as there was an absence of heresies? Truth had to wait for certain Marcionites and Valentinians to set it free. During the interval the gospel was wrongly preached; men wrongly believed; so many thousands were wrongly baptized; so many works of faith were wrongly wrought; so many miraculous gifts, so many spiritual endowments, were wrongly set in operation; so many priestly functions, so many ministries, were wrongly executed; and, to sum up the whole, so many martyrs wrongly received their crowns! Else, if not wrongly done, and to no purpose, how comes it to pass that the things of God were on their course before it was known to what God they belonged? that there were Christians before Christ was found? that there were heresies before true doctrine? Not so; for in all cases truth precedes its copy, the likeness succeeds the reality. Absurd enough, however, is it, that heresy should be deemed to have preceded its own prior doctrine, even on this account, because it is that (doctrine) itself which foretold that there should be heresies against which men would have to guard! To a church which possessed this doctrine, it was written—yea, the doctrine itself writes to its own church—“Though an angel from heaven preach any other gospel than that which we have preached, let him be accursed.”

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXIX

It’s impossible for the Apostolic churches to have apostatized into the same exact faith

Grant, then, that all have erred; that the apostle was mistaken in giving his testimony; that the Holy Ghost had no such respect to any one (church) as to lead it into truth, although sent with this view by Christ, and for this asked of the Father that He might be the teacher of truth; grant, also, that He, the Steward of God, the Vicar of Christ, neglected His office, permitting the churches for a time to understand differently, (and) to believe differently, what He Himself was preaching by the apostles,—is it likely that so many churches, and they so great, should have gone astray into one and the same faith?  No casualty distributed among many men issues in one and the same result. Error of doctrine in the churches must necessarily have produced various issues.  When, however, that which is deposited among many is found to be one and the same, it is not the result of error, but of tradition. Can any one, then, be reckless enough to say that they were in error who handed on the tradition?

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXVIII

The Holy Spirit revealed all truth to the Apostles so that they needed no further revelation of truth

He had once said, “I have yet many things to say unto you, but ye cannot hear them now;” but even then He added, “When He, the Spirit of truth, shall come, He will lead you into all truth.” He (thus) shows that there was nothing of which they were ignorant, to whom He had promised the future attainment of all truth by help of the Spirit of truth.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXII

True doctrine must be tested against the apostolic churches that are in communion with one another

If, then, these things are so, it is in the same degree manifest that all doctrine which agrees with the apostolic churches—those moulds and original sources of the faith must be reckoned for truth, as undoubtedly containing that which the (said) churches received from the apostles, the apostles from Christ, Christ from God.  Whereas all doctrine must be prejudged as false which savors of contrariety to the truth of the churches and apostles of Christ and God. It remains, then, that we demonstrate whether this doctrine of ours, of which we have now given the rule, has its origin in the tradition of the apostles, and whether all other doctrines do not ipso facto proceed from falsehood. We hold communion with the apostolic churches because our doctrine is in no respect different from theirs. This is our witness of truth.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XXI

Only those churches established by the Apostles and their line of succession can be apostolic

…after first bearing witness to the faith in Jesus Christ throughout Judæa, and founding churches (there), they next went forth into the world and preached the same doctrine of the same faith to the nations. They then in like manner founded churches in every city, from which all the other churches, one after another, derived the tradition of the faith, and the seeds of doctrine, and are every day deriving them, that they may become churches. Indeed, it is on this account only that they will be able to deem themselves apostolic, as being the offspring of apostolic churches.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XX

Christ’s substance is both man and God

Christ Jesus our Lord (may He bear with me a moment in thus expressing myself!), whosoever He is, of what God soever He is the Son, of what substance soever He is man and God, of what faith soever He is the teacher, of what reward soever He is the Promiser, did, whilst He lived on earth, Himself declare what He was, what He had been, what the Father’s will was which He was administering, what the duty of man was which He was prescribing; (and this declaration He made,) either openly to the people, or privately to His disciples, of whom He had chosen the twelve chief ones to be at His side, and whom He destined to be the teachers of the nations.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XX