Mortal Sin: Full Knowledge and Deliberate Consent

Just looking for clarification.

Full knowledge - in the context of mortal sin, do we commit mortal sin if we meet the other two conditions, and have knowledge that the action is sinful, or only if we have knowledge that the sin is grave matter?

Deliberate Consent - how much does our emotional state factor in (anger, sadness, sexual tension, etc.)? I’m unsure if I’ve committed mortal sins involving impurity, as I’m pretty sure emotions and sexual tension overwhelmed me, but I’m not completely confident.

Is it possible to have committed mortal sin if we are still unsure of it?

You need the counsel of a holy priest, not random people on the internet. It is best that you discuss sins against chastity with your regular confessor,

I understand, though I still feel my question about full knowledge, general question about our emotional state and mortal sin, and my last question of the original post can be answered. I didn’t mean for this thread to be centered around my potential sins involving impurity, I just included that as an example.

Paragraph 1735 of the Catechism distinguishes grave matter from mortal sin. There are a lot of vague reasons why we may not be culpable or less culpable than for mortal sin.

I have not gotten a complete answer from any priest, bishop, or the USCCB about how to apply 1735.

In the category of psychological reasons for diminished culpability, one priest said that that narrowly means criminal insanity. I object to that on a couple grounds. One, there is a shifting definition of criminal insanity in the U.S. and in countries around the world. There is no one definition of it. second, I object to that because if the bishops of the world wanted to say that, they could have said it was restricted to criminal insanity. Third, I object to it because it appeals to criminal insanity which is defined OUTSIDE of the Catechism. So, it other words, on those terms, it says really nothing.

I think the words of 1735 should mean what they mean in the ordinary sense in English, until proven otherwise. Psychological factors could point to mental stress, the stress of having a disease, to the lack of maturity, etc. Now, scripture says we are not given any temptation that we cannot overcome with God’s grace. but, 1735 gives us a list of reasons why we many not not only succumb to sin, but be less culpable or not culpable for committing what the Church otherwise defines as grave matter.

1735 says that Grave matter does not automatically equate with mortal sin. I believe that is why it uses the term grave matter instead of plainly calling it mortal sin. Grave matter MAY be mortal sin, except for 1735.

1735 says that habit may lessen our culpability for a sin. That same priest says quickly, yes, but we are guilty of forming the habit and not trying to eliminate the habit.

1735 distinguishes (I forget the word) unintentional acts. So, that must mean that the other categories are actually actions that may be been committed intentionally.

Social pressure: a teen might be pressured into stealing to conform to a social group. If that is the only reason for the action, his culpability may be less. Maybe a woman has an abortion due to pressure from her husband, family, boss, or boyfriend, against her free will.

“Other factors” – you tell me.

If 1735 means anything, then we shouldn’t have to confess this grave matter, either. Otherwise, what practical purpose is there in stating this? Remember, it is a part of the deposit of faith. We should not be bullied into rejecting it. I’ve never had a priest ask me if anything I confessed was excluded as a mortal sin by 1735, so as to reassure me that that act was not a mortal sin.

continuing my previous post

I know someone who says that in the fourth grade (more than 50 years ago) of Catholic school, the sister said that an act was a mortal sin only if it was done with the intention of not loving or hurting God.

So, this person does what he/she wants, mentally reserving that he/she doesn’t want to offend God by performing it. Voila. This may qualify as the first condition of 1735, namely ignorance.

If anybody can tell me the name of the book that explains 1735, I want the first copy off of the press.

You need all 3 conditions together.

Grave matter is the easiest to define. It is an act which in its nature is contrary to charity as taught by the Commandments.

Full knowledge is the recognition that what you do is directly against the will of God - but it does not need to be explicitly put into those categories.

Deliberate consent is to will with full knowledge. However, the passions can confuse a person and even totally overpower him to the point where he can’t rationally act at all.

If you knew it was wrong - or ought to have known it was wrong - and had the power and opportunity to choose something else but chose this grave matter, then it is mortal sin.

Encountering temptation suddenly can postpone the deliberate consent, but it does not necessarily do away with it.

And that would be* incorrect.*

One does not have to have such an intention to commit a mortal sin (as St. Pope John Paul II reminded us)


Compendium issued by Pope Benedict XVI
395. When does one commit a mortal sin?**


One commits a mortal sin when there are simultaneously present: grave matter, full knowledge, and deliberate consent. This sin destroys charity in us, deprives us of sanctifying grace, and, if unrepented, leads us to the eternal death of hell. It can be forgiven in the ordinary way by means of the sacraments of Baptism and of Penance or Reconciliation.

396. When does one commit a venial sin?


One commits a venial sin, which is essentially different from a mortal sin, when the matter involved is less serious or, even if it is grave, when full knowledge or complete consent are absent. Venial sin does not break the covenant with God but it weakens charity and manifests a disordered affection for created goods. It impedes the progress of a soul in the exercise of the virtues and in the practice of moral good. It merits temporal punishment which purifies.

There could be more to your particular question that needs to be discussed in more detail- it may be best for you to discuss with your confessor.

Note one can have full knowledge that Y is grave matter when one does Y - even if one does not know the term “grave matter” …ie one knows that say murder is very serious…one can know that such and such is serious and not something little…without knowing the theological terms.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit