Whether heresy is properly about matters of faith?

❌ Objection 1 : It would seem that heresy is not properly about matters of faith. For just as there are heresies and sects among Christians, so were there among the Jews, and Pharisees, as Isidore observes (Etym. viii, 3,4,5). Now their dissensions were not about matters of faith. Therefore heresy is not about matters of faith, as though they were its proper matter.

❌ Objection 2 : Further, the matter of faith is the thing believed. Now heresy is not only about things, but also about works, and about interpretations of Holy Writ. For Jerome says on Gal. 5:20 that "whoever expounds the Scriptures in any sense but that of the Holy Ghost by Whom they were written, may be called a heretic, though he may not have left the Church": and elsewhere he says that "heresies spring up from words spoken amiss." [*St. Thomas quotes this saying elsewhere, in Sent. iv, D, 13, and TP, Question [16], Article [8], but it is not to be found in St. Jerome's works.] Therefore heresy is not properly about the matter of faith.

❌ Objection 3 : Further, we find the holy doctors differing even about matters pertaining to the faith, for example Augustine and Jerome, on the question about the cessation of the legal observances: and yet this was without any heresy on their part. Therefore heresy is not properly about the matter of faith.