How does one commit mortal sin?

I’ll try to explain my question as good as I can:

I know theese are the three conditions that make an act a mortal sin:

An act of grave matter that is...
Committed with full knowledge and...
Deliberate consent.

However, how exactly does this work? For example, if someone did something sinful of grave matter, but kind of was aware that the action taken is sinful, but maybe not so much that the person outright thought: “Yes, I am fully aware that what I am doing is wrong, I understand the situation and the potential consequences” in the **moment **of the sin occuring since he or she was tempted (sexually, for example), and at the same time comitting the sin with some consent, but not full since part of this person tried to fight the sin but ultimately failed.

Would this be considered a mortal sin? Or is it sufficient for the sin to be mortal if you only have a hint of knowledge regarding it is actually a sin in the very moment of it occuring (even if you would fully be aware of it in normal cases when you are not under temptation) as well as just having *some *consent?

You’re correct on your definition of mortal sin 1857 grave matter + knowledge + consent

Because of our fallen nature we have the tendancy to look for ways to excuses our fault. That’s why an important passage is added to the description in #1857. 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.

Here’s an example of what sin did to our 1st parents.

Adam & Eve having committed the 1st sin.
*]What did Eve do 1st, after God questioned her? She said the devil made me do it. iow she wasn’t at fault she blames the devil :rolleyes:
*]What did Adam do 1st after God questioned him? He said the woman made me do it, the one YOU gave me. He blamed Eve & God too. :eek:
[/LIST]bottomline, Mortal sin isn’t hard to commit, it’s easy.

Such as

look at the sins listed here. Are they difficult to commit? No

Gal 5:19 Now the works of the flesh are obvious: fornication, impurity, licentiousness, 20 idolatry, sorcery, enmities, strife, jealousy, anger, quarrels, dissensions, factions, 21 envy, drunkenness, carousing, and things like these. I am warning you, as I warned you before: those who do such things will not inherit the kingdom of God.

Lets tick off the points Paul makes [LIST=1]
*]The works of the flesh are obvious. They’re not a mystery. It doesn’t take discussion or analysis. He says they are obvious. And Paul obviously assumes this is not open to argument.
*]he names sins he’s particularly concerned with because he is seeing the people he’s teaching, are still doing them after he has already warned them that doing them will send one to hell if a person dies with them on their soul. No one can say, they weren’t informed. No one goes away guessing what sins he’s refering to
*]inspite of the 1st warning Paul gave them, some are not taking Paul seriously.
*]notice it doesn’t change Paul’s message to them.
[/LIST]In general, any particular sin that scripture says prevents one from inheriting heaven, THATS a mortal sin. Venial sins don’t keep a soul from inheriting heaven. They will go through purgatory before entrance to heaven, but unconfessed mortal sins otoh, send a soul immediately to hell if one dies with them on their soul.

Scripture gives other lists

*]Titus 3: 10 Reject a factious man after a first and second warning, 11knowing that such a man is perverted and is sinning, being self-condemned.
*]Ephesians 5: 3-5 fornication, covetousness……5 Be sure of this, that no fornicator or impure man, or one who is covetous (that is, an idolater), has any inheritance in the kingdom of Christ and of God.
*]Hebrews 10:25-26 missing mass deliberately, no sacrifice for sin for THEM but a fiery judgement that consumes the adversaries of God.
*]Hebrews 12: 16 - 17 immoraliy, is selling your inheritance
*]Galatians 5: 19 - 21 sexual immorality, impurity and debauchery; 20idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions 21and envy; drunkenness, orgies, will not inherit heaven
*]Romans 16:17… dividers don’t serve our Lord but themselves. Stay away from them. Satan will soon be crushed under your feet
*]Colossians 3: 5-6 immorality, impurity, lust, evil desires and greed, which is idolatry, …rath of God is coming
*]1 Corinthians 6: 9 - 10 no sexually immoral, nor idolaters, nor adulterers, nor male prostitutes, nor homosexual offenders ,ἀρσενοκοίτης arsenokoitēs] 10 nor thieves, nor the greedy, nor drunkards, nor slanderers, nor swindlers, will inherit the kingdom of God.
*]Matthew 15: 19 - 20 murder, adultery, false witness, slander…defile a man
*]2 Peter 2:4-22

In a nutshell…Giving in to a known temptation is not an excuse.

Remember, we are talking about “mortal” - that is deadly sin. Failure should not be considered as an option.

If a person DOES fail…then they should recognize that failure and immediately repent and get to confession at the earliest possible opportunity.

The problem as I see it with these kinds of questions is that they are trying to split hairs. Bottom line - Avoid sin…Avoid ALL sin so far as you are able. Avoid sin because you Love God above all else…not because of some fear that you might loose your salvation…
If you avoid sin out of Love…then you will avoid even small sins as though they were big ones - because you do not wish to hurt Him who you love.
And those times when you do sin…you will hurry to Him in sorrow and repentance.


Do not get bogged down in words like “full” and “deliberate”.
It is quite simple. Assuming no mental incapacity or coercion which may reduce culpability, if you know the Church teaches something is an act of grave matter and you still go ahead and commit the act then you have committed a mortal sin.

I think deliberate or full intent can be a murky issue, and personally I think sins that qualify as truly mortal may be rarer than we think. In cases like addiction where the sin is a compulsion, or situations where we may waffle in our mind but go ahead and do it anyway… I’m not certain that these qualify as mortal. In any case one should repent and get to confession ASAP. But I think what deliberate consent means is that we know, and we don’t care, we’re going to do it anyway.

Just one comment here…When you say, “waffle in our mind but go ahead and do it anyway”, this strikes me as qualifying as - again as you say - “we know, and we don’t care, we’re going to do it anyway”.
Waffling, as I understand it, involves making a decision to do - or not do something…Thus one makes a conscious decision and this qualifies as deliberate consent.


But part of you doesn’t want to do it and feels bad. Just not a big enough part.

Agreed - and this is a good thing…The trick then is to get the balance of the “waffling” shifted so that in future it comes down on the side of NOT doing the sin and avoiding all that feeling bad and consequent guilt.


But because one waffles, does one still commit a mortal sin? Can it be considered full intent?

Waffling is irrelevant.
Full intent simply means committing an act you already knew to be a sin of grave matter and so that is a mortal sin.

Yes - Waffling indicates a decision making process.
The fact that one is waffling, that is debating with one’s self, indicates sufficient knowledge that something is sinful…the choice to proceed over the objections of one’s conscience indicates a free will choice.

As a matter of fact, I would suggest that waffling in this case actually increases culpability rather than decreasing it.


Mortal sin is mortal sin because it’s grave matter and an action that is a grave offense to God. Once a person knows, It’s mortal each and every time it is committed, and certainly before it becomes an addiction. Addiction is merely a side effect.

As Paul puts it, The “acts of the flesh are obvious” [Gal 5:19]. And if one dies in those sins listed, they will not inherit heaven,[Gal 5:21] iow, those sins are not venial but mortal.

If something is obvious, then there is no argument.

Deliberate consent means we choose to do something then do it.

Seriously?! How in the world can this be done? We are NOT perfect, though we may wish we were and of course, this is a lifelong journey so we should be getting holier as we go.

Let’s see, so far today I have committed probably 5 different sins of varying types and degrees. Of course, I am sorry to some extent for them but not always 100% sorry at every moment for it. I want to grow in love of God and others but I am also human and I will never be without sin. Either you are a far better person than me or I am far worse than most. Things like this make me want to go back to protestantism (not really, but I find this rather extreme).

Do you mean - How can we avoid all sin to the extent we are able (which is what I said in my post)?
The answer is always the same…by growing in Love.

We are NOT perfect, though we may wish we were and of course, this is a lifelong journey so we should be getting holier as we go.

Agreed - we are not perfect and it IS a lifelong journey and if we do as you say - get holier as we go - then this means that we love both God and neighbor more perfectly as we go and the more we love - the easier it is to avoid sin.

Let’s see, so far today I have committed probably 5 different sins of varying types and degrees. Of course, I am sorry to some extent for them but not always 100% sorry at every moment for it.

And yet you recognize that the problem is an imperfect Love and you seek to improve this. This approach is quite different than the OP’s queries.

Remember who and what I wrote my reply to. Zoon is seeking a highly legalistic definition of what constitutes mortal sin. Such thinking is, in my humble opinion, not productive. It’s looking in the wrong direction. It is focusing on sin instead of focusing on Love.

I want to grow in love of God and others but I am also human and I will never be without sin.

While I understand this view - it’s not strictly true. If you make a sincere confession, you are free of sin the moment you receive absolution. What we are not free of is the underlying flaws in our character…things we have yet to overcome.
But do not despair - you are doing great and are on the right track.

Either you are a far better person than me or I am far worse than most. Things like this make me want to go back to protestantism (not really, but I find this rather extreme).

I’m sorry I came off like that. I am a terrible sinner…and weak too.
But even a terrible sinner can recognize the right path, even if she or he stumbles badly in trying to follow that path.

Overall, my view on these things is a simple one.
We are on a narrow path and behind us is hell and what is ahead of us is heaven - the narrow gate. If I want to hit that narrow gate, I can’t be focused on what is behind me (temptation and sin). Instead I need to focus on what is ahead of me and how to get there (Heaven and Love).
So instead of trying to define sin to the n-th degree ( something many seem to try) we are better off trying to build love - and as that Love grows then avoiding sin becomes increasingly easy.

As I say - I stumble often - but the path is Love and the Goal is heaven. I invite us all to concentrate on that.


Right. That can yes be a mortal sin.

One can be tempted and resist…can give say half consent …and then later give complete consent.

Or one can be tempted and resist…can give say half consent and comit venial sin --but then one may stop oneself and not give complete consent…

A world of difference between the two.

Though let us “run away” …“flee” not consent at all…

In regards to avoiding sin.

Most important is avoid mortal sin.

Next in importance is “deliberate venial sin”

then other venial sins etc…

Let us yes avoid sin and turn to God with love often.

(knowing that while we are to avoid sin – there will be some “daily sin” in life-- for which we will need to pray “forgive us our trespasses”…)



I like what you said about building love, that makes sense. You didn’t come off as saying you are better. It was me. This is something I am struggling to understand from a Catholic perspective and I overreacted. Sorry.

No problem Anne…I hope that my friends here WILL point out if I am sounding in some way “holier than thou”, or pompous or whatever…Such things help to keep me on the right path.

I too struggle sometimes with the “Catholic perspective”, or more accurately I should say that I struggle with the way the Church explains certain things - mortal sin being one.

If one looks at NT Scripture one can quickly see that the first principle in all of salvation is Love. Love underpins the OT law and prophets (Mt 22:36-40). Jesus came because God so Loved the World (John 3:16). Jesus age a “new commandment” - that we Love one another - and it is by this that others will know that we are His disciples (John 13:34-35). Paul expresses that Love is core and crucial for without it we are nothing (1 Cor 13:1-13). John tell us that God IS love (1 John 4:7-8).

Theologians and others can debate the various intricacies of things, but in our daily walk with Christ it is Love that must take the lead. Love of God and Love of neighbor. With this everything else will eventually come into focus. Without it…well as St Paul says - and I have included in my signature…without Love we are nothing.

(now if I could only apply this consistently in my own life…:blush:)

The Church recognizes the centrality of Love and all of her teachings really spring from and surround this central principle. However I have noticed that sometimes we can forget to communicate this in conversation and in teaching…and then things can become confused.


I keep looking at the title of this thread and asking myself, “Why would someone want *instructions *on how to commit mortal sin?”


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