Fornication, Mortal or grave sin?

I have been in a discussion with a Catholic friend who many times seems very wise.

He has told me that fornication is NOT a mortal sin, but only a grave sin. He has backed this up with the Catechism.

Can anyone help me to understand how it is not a mortal sin? He says that it is because it isn’t specifically mentioned in the 10 commandments…unless I am totally misunderstanding his reasoning…and there is a chance of that.

There is also the problem that the 10 Commandments state: Thou shall not kill. Yet, for self defense of yourself or another, or in war…killing is not a mortal sin.

Thou shall not steal is also a Commandment of the 10, but if a person is starving, and has no other recourse to food except stealing, that makes it not a mortal sin.

So, what is the deal with fornication…which seems that it would be much worse than stealing…even if you planned to get married but were called off to war before your wedding day.

A mortal sin must include three elements. 1) Grave matter, 2) Full knowledge that the matter is grave and 3) full consent of the will to commit the act. Fornication is definitely considered grave matter. (See the Catechism of the Catholic Church) Now if one would know that and give full consent then one would be in mortal sin. The tricky part is always whether or not FULL consent was present. That is why Jesus instituted the Sacrament of Reconciliation. It is a Sacrament of healing and one can know that they are absolved of their sins as well as being able to receive proper direction for overcoming this sin.

So, yes objectively fornication is grave and can potentially be a mortal sin…teachccd :slight_smile:

By the way a grave sin and a mortal sin are exactly the same thing. So if he showed you that fornication was a grave sin in the CCC then he just showed you that it is a mortal sin, as long as it coincides with my post above…Peace, teachccd

I am NOT arguing with you, just trying to learn. Can you tell me where it states that grave sin and mortal sin are the same thing?

In teaching my children CCD, I have read that there are two kinds of sins: venial and mortal. It says nothing about grave sins.

I am aware of the three things that must be present for a mortal sin to indeed be mortal.

Can you help me with my questions?

I think we are getting hung up on semantics. When we talk about grave sin, mortal sin, or deadly sin, we are talking about sins that destroy the saving grace that makes us worthy of Heaven. When we talk about our culpability (how responsible we are for are actions) that act chosen we start plugging in whether it is a grave matter. Fornication is a grave matter. There is no formulation in which it is a class less than that. Fornication with the knowlege it is wrong and with consent = loss of saving grace.

I thought that I was but if you consider that arguing then I will go elsewhere. Sorry that you took my answer in that way…peace…teachccd :blush:

I didn’t take your answer that way. You gave a great answer. I am sorry that I commented in a way that caused you to percieve that I thought you were arguing. Truly, you were innocent of any sort of offfense.

I just knew that I was going to ask questions about your answers…and I didn’t want anyone thinking that I was “disputing” your answers. I only have questions, and I am trying much to understand better exactly what the Church teachings are.

So this is why I started this thread. Please respond. The misunderstanding is my fault. I have been spending too much time on the politics forum.

Looking forward to having further conversations with you.

YOurs in Christ Jesus,

Thank you for responding. If I am correct, my friend is an analyst, and would like to know specifics about what the Church teaches. In other words, if it doesn’t state that fornication is a mortal sin, we cannot take it to be mortal. And that to believe that it is, is going against the Church teaching.

He is truly searching for the truth. He is not going against Church teaching to try to justify fornication, but he is trying to search totally, and follow totally what the Church teaches.

The Church does not teach that certain sins are mortal in and of themselves.

As others have tried to explain, a sin becomes mortal when three conditions (not just the one) are met.

  1. It must be grave matter. This is where the Church offers definitions. Your friend already found that one in the CCC.

  2. It must be committed with full knowledge that the act is against a teaching of the Church or natural law. Since your friend is conversant with the CCC, this seems to be a given.

  3. It must be committed with full consent. Fornication between two consenting adults is almost always with full consent. But there are exceptions such as when one person suffers from a mental illness, when a person is raped, when there are threats to the person or his/her family if he/she does not consent. All of these exceptions could make the matter, while still grave matter, not a mortal sin.

The Church does not rule absolutely on #2 or #3 since that is individual to the state of mind of the individual at the time.

As teachccd said, a grave sin and mortal sin are the same thing. You will not find a classification of sin using the terminology in the Catechism.

Here is the definition of “mortal sin” given in the CCC’s glossary (in the very back of my hard cover copy of the CCC):
Mortal Sin: A grave infraction of the law of God that destroys the divine life in the soul of the sinner (sanctifying grace), constituting a turn away from God. For a sin to be mortal, three conditions must be present: grave matter, full knowledge of the evil of the act, and full consent of the will (1855, 1857).

I grew up in the Baltimore Catechism days - and later, after Vatican II taught CCD for 7 years. What happened was a breakdown in catechesis. Sin itself hardly got mentioned! It wasn’t in the materials. Instead, expressions like “failure to love”, imperfections, selfishness, …" got used. I know I decided finally to use the word “sin”. I recall specifically asking one class of 11th graders about “mortal sin”. They had never heard the expression “mortal sin”. So I asked about “serious sin”, “grave sin”. They hadn’t heard of that either. ( :o & :mad: - at the catechetics, not the kids) : These were kids who had gone to 8 years of Catholic grade school and were in their 3rd year of CCD. So, I explained, - using three terms synonymously: grave sin, mortal sin, serious sin.

Consider that the CCC has all sins falling into one of two classifications - mortal sin or venial sin. Grave matter is always a part of mortal sin. It may or may not be part of venial sin. Subjectively, the only time an act of grave matter would not be a mortal sin is if one of the other two conditions (knowledge or full consent) were not present. Objectively, fornication is “grave matter”.
CCC #2353 * Fornication* is carnal union between an unmarried man and an unmarried woman. It is gravely contrary to the dignity of persons and of human sexuality… Moreover, it is a grave scandal when there is corruption of the young.

This may also be helpful:

**1853 **Sins can be distinguished according to their objects, as can every human act; or according to the virtues they oppose, by excess or defect; or according to the commandments they violate. They can also be classed according to whether they concern God, neighbor, or oneself; they can be divided into spiritual and carnal sins, or again as sins in thought, word, deed, or omission. The root of sin is in the heart of man, in his free will, according to the teaching of the Lord: “For out of the heart come evil thoughts, murder, adultery, fornication, theft, false witness, slander. These are what defile a man.” [Mt 15:19-20]. But in the heart also resides charity, the source of the good and pure works, which sin wounds.


1854 Sins are rightly evaluated according to their gravity. The distinction between mortal and venial sin, already evident in Scripture [Cf. 1 Jn 5:16-17], became part of the tradition of the Church. It is corroborated by human experience.

**1855 ****Mortal sin **destroys charity in the heart of man by a **grave violation **of God’s law; it turns man away from God, who is his ultimate end and his beatitude, by preferring an inferior good to him…

I don’t agree with saying that grave sin and mortal sin are the same.


That’s like saying that coffee beans are the same as a cup of coffee. Yes, without the beans there is no coffee. But to drink a cup of coffee, I must also have ground the beans and added boiling water. If I don’t do the other two things, there is no cup of coffee. If I do them imperfectly, there may be something resembling coffee, but no coffee lover would call it “a real cup of coffee.”

The coffee beans are grave sin. The grinding and the hot water are consent and free choice. The cup of coffee is mortal sin.

The Church and my conscience are the coffee lovers, and Jesus is the ultimate and perfect coffee gourmet - only He knows for sure if it’s *really *a cup of coffee! :thumbsup:

God bless us all, and keep us from sin,


Grave matter and a mortal sin are not the same thing. But a grave SIN and a mortal **SIN **are exactly the same thing. Grave =deadly sin and mortal=deadly sin. So, yes a grave OR mortal SIN are the same thing but grave MATTER and mortal SIN are NOT the same thing. hope that this clears things up…God Bless…teachccd :slight_smile:

No problem. :thumbsup: I got your PM. You have a lot of good answers here. Let me know if I can help any further than what I said in my earlier posts. God Bless…teachccd :slight_smile:

You hold that it is impossible for anyone (individual, or Church) to identify particular acts as a mortal sins. (Since we are incapable of seeing into the mind and heart to judge the degree of knowledge and free consent in the sinner.) That is true in regards to the personal guilt of the individual. But, that is not the way the term “mortal sin” is used when the Church classifies acts contrary to God’s will according to their gravity. You are free to personally disagree with the Church’s definition of mortal sin, but I believe the opening poster wanted to know whether fornication would be classified as a mortal sin, a grave sin, or a venial sin by the Church. There are only two “official” classifications (re gravity) used by the Church - mortal sin and venial sin. The act of fornication is considered a mortal sin.

*1 John 5 16-17 If anyone sees his brother committing what is not a mortal sin, he will ask, and God will give him life for those whose sin is not mortal. There is sin which is mortal; I do not say that one is to pray for that. All wrongdoing is sin, but there is sin which is not mortal. *

The act of fornication is objectively grave matter. When combined with the other two requirements necessary as taught by the Church then it may be a mortal sin. No act, in and of itself, is a mortal sin. While objectively grave and disordered acts such as fornication can be mortal or grave sin, one must possess full knowledge and full consent of the will to define that action as mortally sinful thus completely separating oneself from God.

Someone committing the act of fornication who has no knowledge of its grave nature and/or consequences may not be held culpable and therefore commits a venial sin at worst. This is what the CCC expresses as well as other Church documents. If you can quote otherwise please advise me.

God Bless…teachccd :slight_smile:

A grave is the pit which one is buried in because of their mortality. Grave matter, would then be something which makes a grave…

When combined with the other two requirements necessary as taught by the Church then it may be a mortal sin. No act, in and of itself, is a mortal sin.

So, not even – dying without baptism – is mortal?
Hmmm … that doesn’t sound quite right.

While objectively grave and disordered acts such as fornication can be mortal or grave sin, one must possess full knowledge and full consent of the will to define that action as mortally sinful thus completely separating oneself from God.

Ok. Then why, since babies do not sin with original sin, does dying without baptism constitute eternal separation from God? (We don’t KNOW that he saves every one of them in an unseen baptism…)

Someone committing the act of fornication who has no knowledge of its grave nature and/or consequences may not be held culpable and therefore commits a venial sin at worst. This is what the CCC expresses as well as other Church documents. If you can quote otherwise please advise me.

Do you mean they “will not” be held accountable, or do you mean to say they “might not” be held accountable? Eg: which part of the CCC are you referring to?

Fornication is grave matter – it makes a grave that one can fall into – as in spiritually dead. Whether you fall into it or not, is what constitutes the mortal part.

Like, murder, at least one person goes to the grave – and possibly two.

But, now, I find it rather an act of fancy to think that anyone naturally could think that murder is not wrong. (Mentally handicapped not being a specious argument. They are unable to murder anyway. ) I am not talking manslaughter, but murder. This law, though it may be suppressed, is universal in man.

Perhaps you could improve the details a bit, teachCCD?
I think you are on the right path.

God bless you today.

That is what I have always thought. This is what I was taught. But my friend thought that only things specifically mentioned as one of the 10 Commandments could be considered a mortal sin. Although there are things in the 10 Commandments that could be done without them being mortal sins. Such as, the man who had no other way to feed his family than to steal the food. Or defending the life of yourself or another from being killed…with the only way to do that being to kill the attacker.

And something was mentioned that the only reason that Thou shalt not kill is a mortal sin is because it rejects charity. And my friend didn’t seem to understand how two consenting adults who love each other could be rejecting charity by having sex…even without marriage.
I told him that it would be uncharitable in that without the committment, either could legally just walk away…or that a child could be conceived, and then the father dies, leaving the mother and child unable to have good care. The argument to that was…well, if the man provided life insurance with the woman being the beneficiary, then the charity has not been taken away.

Can anyone offer help?

Someone who commits fornication and has no knowledge that it is sinful doesn’t even sin. But that doesn’t mean it is wrong to say fornication is a sin.

I would have to do a lot of searching to try and track down places where “mortal sin” was used synonymously for “grave matter”. But I do know for certain it was and still is used verbally. If you were to ask a priest or teacher what kind of sin murder is, my guess is their instinctive response would be, “Mortal sin” — not “We don’t know what kind of sin it is. All we can say is that it’s grave matter”.

(It goes without saying that in any conversation or teaching situation where gravity of sin is being discussed, the conditions for mortal sin should/would be included.)

Because there are two classifications of sins (mortal and venial), it’s very typical to want to know which actions fall under which classification. For example, CCD kids will want to know which sins would be considered mortal sins. When you tell them murder, adultery, … you are using those terms objectively, not subjectively. (That is, you are not speaking about a specific act of murder committed by John Smith - which you would not be able to classify.) Likewise, since the terms murder and adultery are used objectively, you can refer to them objectively as mortal sins. There seems to be a sense in which the terms murder/adultery/…, when used objectively, incorporate knowledge and consent (at least in Christian conversation when speaking of them as sins).

Because it has been common usage to make statements such as “Murder/adultery/fornication etc. is a mortal sin” - I guess I would ask you for some source that says, altho such usage is common, it is wrong and not acceptable. Meanwhile, I’ll keep my eyes open to see if I can find usage in Catholic books that support my position.

God bless,

1 Like

I have a twist on this with an example:

Lets say a couple - engaged - falls due to weakness of flesh and or failing to take proper precautions against being over taken by their passions and love for each other though didn’t realize they weren’t taking strong enough precautions.

Though they never meant or intended to fall and have done well to remain chaste for over a year, they did so fall of human weakness and regret it because they know of the spiritual, emotional and physical dangers but feelings were so strong they just couldn’t stop themselves in the heat of the moment.

They never intended to get this far out of control. It sort of snuck up on them over time.

Here is the twist;

There is no scandal to the young. One is physically sterile and cannot conceive and even if this wasn’t the case their disposition is completely open to life.

This fall happens on a Saturday night and they intend to make it right and do better in the future.


1.) Have all three requirements for this fall to be a mortal sin been met?

2.) Are they omitted from communion on the next day - Sunday - until they can receive absolution?

I look forward to your opinions.