full knowledge.

I have this doubt, usually i understand that for mortal sin you need to know that what you are doing is mortally sinful, but i’ve seen some cases of people here asking about stuff they did while not knowing it was a mortal sin, and people tell them to confess, so it brings me this doubt.

What happens when we do something that we don’t know it is a sin?
what happens when that what we do we somehow feel it’s wrong, but then we get the wrong idea that is not, either by others or by ourselves, did we still sin mortally?
what does the hardness of heart is and how do we diferenciate it from just not thinking stuff good enough?

If it is – objectively speaking – sinful, then it is a sin (whether we know it is or not). It can only be a venial sin in that case, though. So, people are right in recommending that a person get to confession: while we’re not, strictly speaking, required to go to confession when we commit venial sin, we are nevertheless recommended to do so.

what happens when that what we do we somehow feel it’s wrong, but then we get the wrong idea that is not, either by others or by ourselves, did we still sin mortally?

If we’re truly convinced that it’s not sinful, then – objectively speaking – we’re wrong, don’t you think? In that case, we have the obligation to ‘fix’ our mistaken notion; that is, we’re obligated to form our conscience properly, so that we correct our erroneous understanding.

In this case, however, could we possibly be considered to have committed mortal sin? That’s an easy question to analyze, but a difficult one to answer: strictly speaking, if we didn’t believe our actions to be sinful, then it is venial sin; yet, as humans, we’re really good at rationalizing things away. It’s pretty easy, sometimes, to convince ourselves that we “really didn’t know” that something was sinful, even if, in the back of our mind, our conscience is sitting there facepalm-ing and quietly reminding us, “yes, yes we did know it’s sinful.”

what does the hardness of heart is and how do we diferenciate it from just not thinking stuff good enough?

In one sense, isn’t the difference simply the distinction between “I know, but I just don’t care” and “I don’t know, but I don’t want to take the time to think it through”…?

Confession can be a lot more than admitting sins and receiving absolution. Many Catholics use Confession as a sort of spiritual counseling session. They bring questions, doubts, and social concerns and the priest is there to help.

Your question would be ideal to bring up in Confession.

I am not a confessor but I can tell you that it is true that a person must know it is a serious sin…must want to do it…and then do it… in order for it to qualify as a serious sin.

If you did something and did not know it was a sin and no other person was hurt and you really didn’t feel guilty about it…then it probably is not a sin.
But just bringing up the subject could mean that someone has some second thoughts about what was done…so best advice is a visit to the Confessional.

As Sister Mary Francis told us in the 6th grade…“If you commit a sin and someone tells you that it is NOT a sin, then that person has the devil in him and will carry that sin for you.”
I don’t know if that is theologically correct, but it made sense to us at that age.

Hardness of heart could be compared to a lax conscience. You keep justifying a bad thing (sin) and soon you have no feelings of guilt or wrong doing. You harden your heart. You have to examine your own conscience. Talk to your conscience…not in front of a lot of people…do it privately.

“Hey conscience, was what I did wrong?”
“Yes”.
“But I didn’t mean it…”
“It was still wrong”
“But they deserved it”
“Yeah, but that doesn’t make it right”
“Ok what should I do?”
“Go to confession.”

Luckily, we are not the judge in the tribunal of the confessional; the priest, representing the Church, is. If we commit an objective sin, but do not know it to be a sin, then that sin is venial. Properly speaking, venial sins need not be confessed, but it is a prudent and oft-counseled practice to confess one’s chief venial sins at confession anyway.

If one of our past sins was ordinarily a mortal sin and we did not even at the point realize it to be mortal, then we are obliged to confess it at our next confession, even though the sin was not in this circumstance mortal. Confessors use these opportunities to form in us better consciences, and such an example that you offer can surely lead to much growth in morality.

God bless.

If I was say clueless that something was a sin when I did it thinking it was good - I did not even commit necessarily even a venial sin.

If I did not commit a mortal sin – even though the matter was grave – due to not having the needed knowledge or giving complete consent – I am NOT obliged to confess that in my next confession. One is ONLY obliged to confess mortal sins that one has committed.

Now I am not referring to say “feigned ignorance” etc. But authentic being in good faith.

Now that being said - it can be good to confess that which was objectively grave in the past even though one is not sure one committed a mortal sin at that point. Noting of course that one is not sure it was mortal etc. (though those who are scrupulous may need to be advised otherwise by their regular confessor).

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