Tertullian, Prescription against Heretics 2

Fever, that final installment in the grim ledger of deadly and torturous exits allotted to humanity, does not shock us simply because it exists; it exists. Nor does it shock us because it kills; that is its job. Heresies, engineered to rot and destroy faith, operate on the same brutal logic: if we tremble at what they *can* do, we must first tremble at the fact that they *are*; for as long as they exist, they possess the power to act, and as long as they can act, they exist. Yet we treat fever as the evil it is—rotten in cause and in force—abhorring it rather than gawking at it, and we take whatever precautions we can, precisely because we lack the power to abolish it. Heresies, however, inflict eternal death and the fiercer heat of a greater fire, and yet certain people choose to marvel at their destructive reach rather than avoid it, even though the power to avoid them lies in their own hands.

They will prevail only as long as people marvel that they prevail at all. Either the spectacle of marveling becomes a stumbling block, or they marvel *because* they have already stumbled, imagining that such potency must spring from some kernel of truth. It is a marvel, certainly, that evil wields power; unless, of course, heresies only flex their muscle among those who have no strength in the faith. In the arena, a fighter often wins not because he is strong, nor because he is invincible, but because the man he beat had no strength at all; match that same victor against a truly strong opponent later, and he goes down defeated. Heresies work the same way: they draw their only power from the weaknesses of certain people, prevailing over nothing at all, provided they never run into a robust faith.