What sins are considered mortal?

My mum and I have been discussing this and are having difficulty deciding which sins are mortal and which are venial. Can anyone tell me if there is a list or something like that of sins that are mortal?


No there is not a list but here are some guidelines that will help.


Here is a link to a searchable CCC on line. Most important for a Catholic reach for the CCC and the Bible when one has a question!


Begin with the Catechism section on sin

It begins here


You are not going to find an official list.

The Catechism will help you find what is grave or serious matter. For a sin to be mortal, it must be grave matter and be:

**1859 **Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart do not diminish, but rather increase, the voluntary character of a sin.

There are many examinations of conscence available on line, these assist you in seeing sin in your life.


For a sin to be mortal, it must meet three conditions.

  1. It must be a grave offense (ie. Breaking one of the Ten Commandments,)

  2. You must have knowledge that what you are doing is a sin.

  3. You committ this sin with free will. (ie. "Nobody is holding a gun to your head forcing you to committ this sin, etc.)

I would search the internet for documents on examining one’s conscience. Then you will have a better understanding on what is a mortal sin.

This always used to be a problem for me. I understood the requirements for a mortal sin, but there isn’t a list of what is “grave matter.” In the Catechism it lists a lot of things as “grave matters” which, committed with full knowledge and complete consent, would be mortal sins. Fr. Richards has a good list of sins (oxymoron?) on his website (thereasonforourhope.org/pdfs/14.pdf) but not all of them are grave (though many of them are) and it is written mostly for teenagers.

Missing Mass on a Holy Day of Obligation or Sunday is grave. Sex outside of marriage, use of artificial contraception, drunkenness, etc. are also grave. And receiving Holy Communion while not in a state of grace (if you’ve committed a mortal sin and haven’t yet gone to confession) is grave. There are many more, of course, but I think those are some common ones.

There can be no official list because what is grave for me may not be grave matter for you… here is an example… repetitive venial sin can become grave matter if the penitent does not take steps to correct the behavior.

If I had a problem with telling stories… not out and out lies… just twisting the facts a bit does that constitute grave sin? How about if I do this in the context of writing childrens books on morality? What if it is in the context of ruining the reputation of someone I dislike? Is it then grave sin? Where is the line?

Or what if I take a pencil home from work? Is that the same gravity as embezzling company funds? They are both stealing right? What if pencils were ok so I took 1 pencil home every day and when I had a set I sold them on ebay to make money?
The danger of asking for a list is that there are some people who will push their limits as far as they can without crossing the line… at what point is pushing limits sinful? It goes on and on…

Difficult Question In The Sense That You Can Haunt Yourself To Anxiety With The Answer. Yeah The 3 Basic Things In The Catechism Apply: Grave Offense, Full Conscience Knowing It Is Wrong, & Firm Free Will To Commit. Problem Is: Who Defines Grave? On 1 Hand You Can Give Yourself An Anxiety Attack If We Tally Every Little Error We Make. There Is No List. More Perplexing–explain The Person Who Steals A Bottle Of Milk During A Hurricane Crisis After All The Power Has Gone Out & All The Infrastructure Is Destroyed Including Of Course The Grocery Store Is Kaput & The Food Is Spoiling. Go Ask God. Then There’s The Nuremburg Defense. If God Already Knows We Are So Fallible Perhaps We Should Just Lock Ourselves Up In A Windowless Room & Stay There For Eternity. Don’t Forget That Even Moses Killed A Man. Then Again Even A Mortal Sin Can Be Forgiven On The Deathbed. The Only Unforgiveable Sin Is Rejection Of The Holy Spirit & I Am Not Sure What That Exactly Means.

It Is Very Difficult To Type With Caps For The First Letter Of Each Word - and even MORE diffucult to read.

Maybe use plain ole normal typing, with paragraphs?

Rejection of the Holy Spirit (in this instance), I think means a final and total despair and willful rejection of the grace of the Holy Spirit to forgive our sins. This occurs (I believe) at the moment of death.

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