The battle to refute heresies and to affirm and apply orthodox doctrines is primarily an exegetical battle. That is not to say that matters of synthesis, theology, and philosophy are far removed from the fight. They always lie close at hand. But as Hilary of Poitiers memorably put it:
...there have risen many who have given to the plain words of Holy Writ some arbitrary interpretation of their own, instead of its true and only sense, and this in defiance of the clear meaning of words. Heresy lies in the sense assigned, not in the word written; the guilt is that of the expositor, not of the text.There is a great danger that texts have not only be wrongly interpreted, but also read through the lens of a world view that has been imposed upon, rather than arisen from, the text. Anyone engaged in polemical theology must be aware of this danger.
The goal is to show that the words of Scripture cannot bear the heretical meaning imposed upon them, that at the exegetical level error offers abitrary interpretations. Of course, there is a short route from collecting a few texts together to the construction of an non-negotiatible hermeneutical grid through which all texts are then filtered.
Not that those with an orthodox theology are themselves entirely free from the danger of misinterpreting the text, or that the texts are always used in the right way to support the right doctrines. To have the humility to admit this should not be confused with opening the door to the teeming hordes of postmodern special interest groups who want to bend the words of Scripture to fit their particular agendas.
I know that every time that I get into my car I can take a wrong turning, but not every wrong turning is a big deal, and knowing that I can take a wrong turning is not the same as actually taking one and protesting that it is in fact the right way. Something of Hilary's attitude is essential for every expositor of the sacred text:
We look to Thee to give us the fellowship of that Spirit Who guided the Prophets and the Apostles, that we may take their words in the sense in which they spoke and assign its right shade of meaning to every utterance.
All things in Scripture are not alike plain in themselves, nor alike clear unto all: yet those things which are necessary to be known, believed, and observed for salvation, are so clearly propounded, and opened in some place of Scripture or other, that not only the learned, but the unlearned, in a due use of the ordinary means, may attain unto a sufficient understanding of them.
Does that mean that arriving at sound conclusions merely follows from a surface reading of the text? Sometimes, to be frank, it does.
The truth of God, which enable us to speak of some doctrines as orthodox and others as heretical, is indelibly woven in to the very fabric of the text. No amount of talk about the historic development of Christian doctrine should be allowed to obscure the fact that the doctrines we are to believe, teach and confess are to be done so on the basis that they are found in the Word of God written.
Given that Scripture presents us with its own doctrinal vocabularly and categories the choice of heretics is to give the words and concepts of the Bible distinctly unorthodox meanings. Thus, in Church history Paul's catholic, creedal, affirmation that "Christ died for our sins according to the Scriptures" (1 Cor. 15:3) has been assigned totally opposite meanings. To the Socinians and their successors it is interpreted in such a way as to deny penal substitutionary atonement. That is why combatting error and affirming truth must get down to the issue of "what do these words mean" and not simply repeat them.