From “The christian in Complete Armour”
Satan comes as a serpent in the persons of false teachers, and by them labours to deceive us with error for truth. To defend us against this design, it is necessary that we be girt with truth in our understanding. I remember Tertullian, speaking of some heretics, as to their manner of preaching, said, "They teach by persuading, and do not by teaching persuade."
Truth is loved and prized only by those that know it; but not to desire to know it is to despise it. Every Christian should labour for an established judgement in the truth on account of the damming nature of false doctrines – remembering that false doctrines hunt for the souls of men as well as any other sin. A corrupt judgment in foundation-truths kills as sure as a rotten heart. This is not believed by some, who, though very strict in their lives, and apparently as tender in matters of morality as Lot was of his guests, yet are very loose in their principles and judgments, exposing them, as Lot later exposed his daughters, to be defiled with any corrupt doctrine that comes to the door.
They would make us think that the matter of truth men played but at small game, and that their souls were not at stake, as in other sins. Yea, there are some that make as many ways to heaven as the scriptures tell us there are roads to hell. Truths, in many professing Christian minds, are not as stars fixed in the heavens, but are like meteors that dance in the air. Therefore, humbly beg an established judgment of truth from God. But lay this deep in thine heart, that God, who gives an eye to see the truth, must also give a hand to hold it fast when we have it.
Keep therefore thine acquaintance with God, or else God’s truth will not keep her acquaintance long with thee.