(a) One must know that one’s belief is opposed to divine revelation or to Catholic faith. Hence, those who were born and brought up in Protestantism, and who in good faith accept the confession of their denomination, are not formal but material heretics. Even those who are ignorant of their errors through grave fault and who hold to them firmly, are guilty, not of formal heresy, but of sinful ignorance (see 904 sqq.) (b) One must willingly consent to the error. But for formal heresy it is not required that a person give his assent out of malice, or that he continue in obstinate rejection for a long time, or that he refuse to heed admonitions given him. Pertinacity here means true consent to recognized error, and this can proceed from weakness (e.g., from anger or other passion); it can be given in an instant, and does not presuppose an admonition disregarded. Hence, if one sees the truth of the Catholic Church, but fears that assent will involve many obligations and out of weakness turns away from the truth, one then and there pertinaciously consents to error. 830. Examples of material heresy are: (a) Catholics who deny certain dogmas of faith, because they have not been well instructed, but who are ready to correct their errors, whenever the Church’s teaching is brought home to them; (b) non-Catholics who do not accept the Catholic Church, but who have never had any misgivings about the tenets of their own denomination, or who in doubts have searched for the truth to the best of their ability. 831. The sinfulness of heresy is as follows: (a) formal heresy is a grave sin, as was said above regarding unbelief in general (see 819; Tit., iii. 10); (b) material heresy is no sin at all, if the ignorance is invincible; it is a grave or a venial sin, according to the amount of negligence, if the ignorance is vincible. 832. Circumstances of the sin of heresy are of various kinds. (a) Circumstances that change the species. Most theologians hold that the particular article denied, or the particular sect adhered to, does not constitute a particular species of heresy, and hence that in confession it suffices for one to accuse oneself generically of heresy. (b) Circumstances that aggravate the sin. The facts that heresy is external, that it is manifested to a large number, that it is joined with apostasy and adhesion to an heretical sect, etc., increase the accidental malice of this sin. (c) Circumstances that multiply the number of sins. It seems that when several articles or defined truths are denied at the same time, so many numerically distinct sins are committed (see 219). Example: Titus says: “I do not accept the Resurrection, either of Christ or of the dead.” The act is one, but two sins are committed.