Whether heresy is a species of unbelief?

❌ Objection 1 : It would seem that heresy is not a species of unbelief. For unbelief is in the understanding, as stated above (Question [10], Article [2]). Now heresy would seem not to pertain to the understanding, but rather to the appetitive power; for Jerome says on Gal. 5:19: [*Cf. Decretals xxiv, qu. iii, cap. 27] "The works of the flesh are manifest: Heresy is derived from a Greek word meaning choice, whereby a man makes choice of that school which he deems best." But choice is an act of the appetitive power, as stated above (FS, Question [13], Article [1]). Therefore heresy is not a species of unbelief.

❌ Objection 2 : Further, vice takes its species chiefly from its end; hence the Philosopher says (Ethic. v, 2) that "he who commits adultery that he may steal, is a thief rather than an adulterer." Now the end of heresy is temporal profit, especially lordship and glory, which belong to the vice of pride or covetousness: for Augustine says (De Util. Credendi i) that "a heretic is one who either devises or follows false and new opinions, for the sake of some temporal profit, especially that he may lord and be honored above others." Therefore heresy is a species of pride rather than of unbelief.

❌ Objection 3 : Further, since unbelief is in the understanding, it would seem not to pertain to the flesh. Now heresy belongs to the works of the flesh, for the Apostle says (Gal. 5:19): "The works of the flesh are manifest, which are fornication, uncleanness," and among the others, he adds, "dissensions, sects," which are the same as heresies. Therefore heresy is not a species of unbelief.