What exactly is heresy? What is a mortal sin? I'm still not quite sure

I was looking at a list of mortal sins, and one of the sins said:
**Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same; **

So my first question is, can someone who hasn’t been baptised commit heresy?

My second question is about the three points of a mortal sin, its a grave matter, and committed with full knowledge and consent. Let me give an example, if someone doesn’t believe masterbation is a mortal sin, are they or aren’t they in breach of the second point, full knowledge? If someone doesn’t believe in God, are they in breach of full knowledge?

My third question involves Catholic dogma. I know de fide and fides ecclesiastica beliefs are Catholic dogma, but are sententia fidei proxima and theologica certa Catholic dogma?

My fourth question is a summary of the prior three. If someone who has been baptised denies a Catholic dogma, believing it is not a Catholic dogma, even if they’ve been shown it was, are they in breach of all three points of a mortal sin? And would it be wise to advise them you believe they are in a state of mortal sin for heresy?

I’m asking because I don’t want people to go to hell, and I want to be able to tell them they’re in a state of mortal sin if they are in a state of mortal sin. I recognize it’s hard to tell, but I wonder if its possible.

I believe you have the wrong objective. Not only that, since you don’t know anyone’s knowledge or level of consent, you have no way of knowing if someone else is in the state of mortal sin.

In regard to someone’s belief of the teaching on the sinfulness of an act, belief is not a factor. They only need to know that it is gravely sinful.

Our objective ought to be to get ourselves to heaven, leading as many others, particularly any that we have been put in charge of, as we can.

But how can we help anybody get to heaven if we can’t tell them they’re in danger?

I don’t think you will help anyone by declaring that they are in mortal sin. If fact, you will likely put them on the defensive and harden their position.

We help them by living out faithfully the great commandments to love God and neighbor, while being ready to explain the reason for our hope of heaven.

Are you aping a flibbertigibbet? If you pay attention you may learn the answers to what you are after.

In post #3, 21/1/11, 5:16 pm in the thread Are there any mistakes in Catechisms? You were answered thus:

Are there any mistakes in Catechisms? What they say is to be taken as correct for Catholics, right?

The Apostolic Constitution by Pope John Paul II states that it is “a sure and authentic reference text for teaching Catholic doctrine…” There are no serious “mistakes” that misinterpret doctrine or dogma.
Can I believe someone is a heretic if they deny what the Catechisms say on a particular issue?
Please see Canon 751: “Heresy is the obstinate denial or doubt, after baptism, of a truth which must be believed by divine and Catholic faith.” (A dogma).

Therefore, it is heresy ONLY if a person dissents from dogma, not infallible doctrine which belongs to category two – to be firmly embraced and held; nor to category 3 which is non-infallible doctrine – the category 3 truths are non-definitive (non-infallible) and require intellectual assent (“loyal submission of the will and intellect”, Vatican II, Lumen Gentium 25), not an assent of faith.

So, no it is not good to go around either believing or saying that anyone is a “heretic”. There may be good reason to suggest that it is heresy if the fact in Can 751 is evident, with willful and clear knowledge of the gravity of the denial or doubt.

We can help only to the extent that the questioner pays attention.

Greetings, brother!

Before baptism, the sin-equivalent to heresy is simply called unbelief. Heresy is worse than unbelief, defined in this sense, because “it would have been better for them never to have known the way of righteousness than after knowing it to turn back from the holy commandment delivered to them” (2 Peter 2:21).

The Catechism says that “no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man” ( 1860CCC). And Paul says that “what can be known about God is plain to them, because God has shown it to them” (Romans 1:19).

Have you read this: Commentary on the Professio Fidei? It may help answer some of these types of questions for you.

One of the spiritual works of mercy is to “admonish sinners.” Because of the number of mitigating factors, subjectively speaking, it may be best to simply tell the person what the three criteria are, and to warn him that the sin that he is involved in is objectively grave and hateful to God. But you know the person, so you will know how best to approach him. I respond better to direct and stern rebuke. But this cannot be said for everyone. :o

Welcome to the forums and the Catholic Church! I was introduced to Christ as an adult through Calvinism too, praise be to God!

Your brother in the LORD,

Here is the entry on “Heresy” from Modern Catholic Dictionary by Fr. John A. Hardon, S.J. :

In the Roman Catholic Church, heresy has a very specific meaning. Anyone who, nominally a Christian, pertinaciously denies or doubts any of the truths that must be believed with divine and Catholic faith is considered a heretic. Accordingly four elements must be verified to constitute formal heresy;
previous valid baptism, which need not have been in the Catholic Church;
external profession of still being a Christian, otherwise a person becomes an apostate;
outright denial or positive doubt regarding a truth that the Catholic Church has actually proposed as revealed by God;;
and the disbelief must be morally culpable, where a nominal Christian refuses to accept what he knows is a doctrinal imperative.

Objectively, therefore, to become a heretic in the strict canonical sense and be excommunicated from the faithful, one must deny or question a truth that is taught not merely on the authority of the Church but on the word of God revealed in the Scriptures or sacred tradition. ** Subjectively a person must recognize his obligation to believe. If he acts in good faith, as with most persons brought up in non-Catholic surroundings, the heresy is only material and implies neither guilt nor sin against faith**.

Hope this answers most of your questions.

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