They put forward the Scriptures, and by this insolence of theirs they at once influence some. In the encounter itself, however, they weary the strong, they catch the weak, and dismiss waverers with a doubt. Accordingly, we oppose to them this step above ,all others, of not admitting them to any discussion of the Scriptures.
If in these lie their resources, before they can use them, it ought to be clearly seen to whom belongs the possession of the Scriptures, that none may be admitted to the use thereof who has no title at all to the privilege.
I might be thought to have laid down this position to remedy distrust in my case, or from a desire of entering on the contest in some other way, were there not reasons on my side, especially this, that our faith owes deference to the apostle, who forbids us to enter on "questions," or to lend our ears to new-fangled statements, or to consort with a heretic "after the first and second admonition," not, (be it observed,) after discussion. Discussion he has inhibited in this way, by designating admonition as the purpose of dealing with a heretic, and the first one too, because he is not a Christian; in order that he might not, after the manner of a Christian, seem to require correction again and again, and "before two or three witnesses," seeing that he ought to be corrected, for the very reason that he is not to be disputed with; and in the next place, because a controversy over the Scriptures can, clearly, produce no other effect than help to upset either the stomach or the brain.
Now this heresy of yours does not receive certain Scriptures; and whichever of them it does receive, it perverts by means of additions and diminutions, for the accomplishment of it own purpose; and such as it does receive, it receives not in their entirety; but even when it does receive any up to a certain point as entire, it nevertheless perverts even these by the contrivance of diverse interpretations. Truth is just as much opposed by an adulteration of its meaning as it is by a corruption of its text. Their vain presumptions must needs refuse to acknowledge the (writings) whereby they are refuted. They rely on those which they have falsely put together, and which they have selected, because their ambiguity. Though most skilled in the Scriptures, you will make no progress, when everything which you maintain is denied on the other side, and whatever you deny is (by them) maintained. As for yourself, indeed, you will lose nothing but your breath, and gain nothing but vexation from their blasphemy.
But with respect to the man for whose sake you enter on the discussion of the Scriptures, with the view of strengthening him when afflicted with doubts, (let me ask) will it be to the truth, or rather to heretical opinions that he will lean? Influenced by the very fact that he sees you have made no progress, whilst the other side is on an equal footing (with yourself) in denying and in defence, or at any rate on a like standing he will go away confirmed in his uncertainty by the discussion, not knowing which side to adjudge heretical. For, no doubt, they too are able to retort these things on us. It is indeed a necessary consequence that they should go so far as to say that adulterations of the Scriptures, and false expositions thereof, are rather introduced by ourselves, inasmuch as they, no less than we maintain that truth is on their side.
Our appeal, therefore, must not be made to the Scriptures; nor must controversy be admitted on points in which victory will either be impossible, or uncertain, or not certain enough. But even if a discussion from the Scriptures should not turn out in such a way as to place both sides on a par, (yet) the natural order of things would require that this point should be first proposed, which is now the only one which we must discuss: "With whom lies that very faith to which the Scriptures belong. From what and through whom, and when, and to whom, has been handed down that rule, by which men become Christians?" For wherever it shall be manifest that the true Christian rule and faith shall be, there will likewise be the true Scriptures and expositions thereof, and all the Christian traditions.
-- Quintus Septimius Florens Tertullianus, The Prescription against Heretics, Chs. 15-19
The moral of the story for Catholics: it is pointless to dispute the Scriptures with those who don't even claim apostolic succession, including most prominently Protestants. To concede their authority to interpret Scripture is to yield more than they deserve.
EDIT -- Quick clarifications: Just to be clear, I don't mean that all Protestants do this. There are many Protestants who, to varying extents, identify the action of ministers or the church as a whole with that of Christ in the Holy Spirit. But those who make no claim for human beings acting as Christ may (and ought) to be freely rejected.
