Question about mortal sin


I am new to the forum. I just came back to the church 1 year ago. I am really delighted to have rejoined the church and have become active an a prayer group and am gaining a lot spiritually from it.

One problem I have is discerning the difference between venial and mortal sin.

I understand the 3 conditions necessary for mortal sin, but its the application of them that I have difficulty with. I’ve seen varying opinions on the forum about how easy/difficult it is to commit a mortal sin and I am totally confused about the issue.

One problem I have difficulty with is in the case of any immoral thoughts, do you have to know at the time of thinking the thought that it is grave matter (i.e. reflect on the fact that continuing the thought would be a mortal sin) , or would a situation where it would be common sense to know that such a thought is grave matter, but you didn’t reflect on this fact at the time of actually thinking the thought, be considered a mortal sin. The key question here is “do you have to reflect AT THE TIME you are having the thought that it is a mortal sin”.

Also, to fulfill the 3 conditions, do you have to know that it is grave matter, or simply know that it is sinful?


A rule of thumb:
Any breaking of the Ten Commandments is a mortal sin.

Deliberate sinful thoughts to do with the commandments is a mortal sin, eg deliberately entertaining impure thoughts or fantasies about someone.

A temptation is not a sin, but it becomes one if you deliberately intentionally wilfully mull over commiting the temptation (eg seriously thinking of committing an abortion)

The commandments also bring with them other commandments, eg it to commit adultery also means it’s a mortal sin to carry out gay intimate acts with someone, premarital relations with someone, or masturbation, or looking at nude or semi clad photos, or scenes like that on television deliberately,

The first commandment ‘You shall not have strange God’s before me’ also means, aetheism is a mortal sin (it denies the truth of a God who has left His evidence and gifts all around you), it also means participating in other religions or New Age (yoga, reading star signs, hypnotism, Pilates, the Vatican has said all these things are seriously pagan and occult -people have had to receive exorcisms from them from the Vatican’s exorcists). It also means to not go to mass weekly and receive communion in a state of grace (without unconfessed mortal sins) , not going to confession for years , is a mortal sin

All stealing or lying (no matter how small, is a mortal sin)
This help?

I suppose the main issue I have is how easy/difficult it is to commit a mortal sin.

I’ve made a decision to stay away from the obvious mortal sins that the church have identified.

However, I seem to be constantly convincing myself that everything is possibly a mortal sin.

Also, there seem to be two varying opinions on the first criteria for mortal sin.

The first is that you have to be aware that it is gravely sinful. i.e. grave matter. In this case, I’ve often heard people say that the rule of thumb is that if you didn’t know that its a mortal sin, it probably wasn’t.

On the other hand, I’ve heard it said that you only have to know that the act is sinful and do it willingly for it to be a mortal sin. If you thought perhaps that an act was sinful, (but were not aware that it was a serious sin i.e. grave matter) that you could have still committed a mortal sin if the sin you committed was grave matter and the other two conditions were met.

I have been told by priests that if you committed a mortal sin you would know it. There would be no doubt.

any thoughts…

Welcome back to the Church!

Firstly, what the Catechism of the Catholic Church says about sin:

We need to be primarily aware of God’s love and forgiveness, to prevent ourselves from succumbing to scrupulosity, living in fear and seeing sin in places where is actually is not.
Your priest in Confession can help you to find the true balance.

You are aware of your human weakness. As soon as you become aware of immoral thoughts, then ask God’s help, and do what you can to distract yourself from any thoughts that might lead to sin. Temptation isn’t sin, unless we deliberately seek it, it becomes sin when we accept a temptation and dwell on it.

It can be difficult to overcome if it’s a habit, but never give up hope, try, and try again.

Remember always, the two commandments of Jesus that sum up the commandments, to love God above all, and others as ourselves.
Remember that when Jesus described the judgement of souls His stated criteria was whether or not we have lived lives of practical kindness to others, which can be as small as a smile and kind word, but also necessary in other needed practical acts of kindness. He said that what we do kind deed for other, we are also doing them for Him, in loving them we are also loving Him. This focus draws oneself out of that focus on self that is more inclined to lead to sin.

Matthew 25:31-46

The Judgement of the Nations

‘When the Son of Man comes in his glory, and all the angels with him, then he will sit on the throne of his glory. All the nations will be gathered before him, and he will separate people one from another as a shepherd separates the sheep from the goats, and he will put the sheep at his right hand and the goats at the left. Then the king will say to those at his right hand, “Come, you that are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world; for I was hungry and you gave me food, I was thirsty and you gave me something to drink, I was a stranger and you welcomed me, I was naked and you gave me clothing, I was sick and you took care of me, I was in prison and you visited me.” Then the righteous will answer him, “Lord, when was it that we saw you hungry and gave you food, or thirsty and gave you something to drink? And when was it that we saw you a stranger and welcomed you, or naked and gave you clothing? And when was it that we saw you sick or in prison and visited you?” And the king will answer them, “Truly I tell you, just as you did it to one of the least of these who are members of my family, you did it to me.” Then he will say to those at his left hand, “You that are accursed, depart from me into the eternal fire prepared for the devil and his angels; for I was hungry and you gave me no food, I was thirsty and you gave me nothing to drink, I was a stranger and you did not welcome me, naked and you did not give me clothing, sick and in prison and you did not visit me.” Then they also will answer, “Lord, when was it that we saw you hungry or thirsty or a stranger or naked or sick or in prison, and did not take care of you?” Then he will answer them, “Truly I tell you, just as you did not do it to one of the least of these, you did not do it to me.” And these will go away into eternal punishment, but the righteous into eternal life.’

May God continue to bless you, having given you the wonderful gift of your return to the Sacraments.

Kind wishes,

Let’s see if we can shed a bit of light here for you…
Condition one - Gravity - This is the most objective of the aspects. A sin is more or less grave based on several factors, who is harmed and to what degree. However - Gravity alone will not make something mortally sinful because the two other conditions are required.
Condition two - Knowledge sufficient to know it is a sin. So if one knows it is sinful AND the act is grave (harmful to self or others)…the second condition is met.
Condition three - free will. Basically this means you are free to act (or not act).

This is my brief take on the conditions…but I believe there is a deeper underlying aspect that is truly at the root of the matter.
That is Love…Agape.
the whole issue of whether we are in mortal peril or not revolves around the two great commands of Love. Love God and Love neighbor as ourselves. If we focus on and then act out of Love for God then we will not do that which offends him. Thus, we will never commit mortal sin.

Just some thoughts


Let me extend a very warm Welcome Home to you.

One problem I have is discerning the difference between venial and mortal sin.

The best place to get help with that is with your confessor/spiritual director.

I understand the 3 conditions necessary for mortal sin, . . .

One problem I have difficulty with is in the case of any immoral thoughts, do you have to know at the time of thinking the thought that it is grave matter

Yes, you can’t ‘accidentally’ commit a mortal sin, it has to be intentional.

Also, to fulfill the 3 conditions, do you have to know that it is grave matter, or simply know that it is sinful?


Yes you have to know it is a grave sin.

Again, I’d suggest you discuss this at confession so you can get a correct understanding of how to grow in holiness without worrying yourself unnecessarily.

Thanks for all your comments.

I seem to be constantly rethinking internal conversations in my head to check if I have committed a mortal sin.

Also, I sometimes take the teaching of the church so literally that it would be impossible to live in the modern world and remain true to catholic values. However, I normally finally realise that I was worrying or fussing over nothing.

While worrying about these issues, I often realise in my heart that I am taking church teaching too literally (e.g. yesterday I spent ages worrying over occasions of sin. On reflection, I identified some realistic guidelines for proximate and remote occasions of sin).

However, during the internal dialogue, I knew in my heart that I had no serious intention of avoiding the possible occasion of sin as it was not realistic. In reality, my understanding is that this is not what’s expected anyhow. However, did I commit a mortal sin by thinking that I would not avoid an occasion of sin before I had fully convinced myself that this was ok based on the fact that it was remote.

Hope this makes sense

First of all - No you did not commit a mortal sin in your thought process.

Overall it appears that there is one of two things going on here…

  1. You are trying to absorb too much church teaching all at once and it is confusing you
  2. You have a tendency to scruples.

If number two - you need to seek out a good regular confessor to help you.
If number one (which I think is more likely) - you need to back off a little bit. Start with the foundation of Love.
Don’t try to think if things in terms of sin. Instead, think of things in terms of how loving a given thing is. This will go a long way toward helping you to understand the other things.


Thanks. That makes a lot of sense. I think it is a bit of both.

What typically happens is that I start to wonder if I’ve committed a mortal sin - usually in my thought process. I look logically at the situation and find that it’s not likely. However, I seem to have to keep reviewing the same thought process to re-assure myself. It’s like I have to prove to myself that I have not sinned. My main reason for this is that I’m afraid of making an invalid confession. However, common sense tells me that these could not all be sins.

One example is where I had a thought that I know logically could not be sinful. Again, I kept having to review the thought to prove to myself that it wasn’t sinful. During the process, I actually consented to the thought. I then deduced that technically I must have committed a mortal sin as I understand that if you’re not sure whether something is a mortal sin or not and go ahead and do it without checking that you have committed a mortal sin. I would consider this more of a “technicality” than a sin, as I really don’t feel I’ve done anything wrong.

I seem to spend my time trying to work out what I would consider technicalities my mind.

I also suffer from intrusive thoughts and I know they are not sinful. However, I find there are a lot of gray areas. I get the urge to think bad thoughts and for a few seconds (3 - 5) I know I shouldn’t be thinking this but I do it anyhow. I don’t enjoy or agree with any of the thoughts but I am aware that I’m thinking them myself. Then finally, I manage to stop.
I’m never sure if this is full or partial consent.

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