Mortal sin ans sins of the heart

I’m having trouble deciding what is and what is not a mortal sin. I understand the basics - full knowledge, determined consent, and grave matter. My reasoning on the full knowledge is that I have read the Bible several times so I really can’t claim ignorance. As for grave matter if masturbation and missing church is a grave matter than virtually everything is. This really means that everything hangs on determined consent. I’ve had the misfortune of living in a college dormitory and a military barracks. If I don’t discipline my mind it will eventually go to one of two things - obscene humor or resentment and anger. Based on Jesus’ sermon on the mount that indicates that thoughts do matter it is reasonable to believe that these thoughts are sinful. As both the obscene humor and anger are accompanied by thoughts that would be sinful to even consider actually doing.
On the one hand I can say that the fact that the thoughts occur is evidence that I consented to them. On the other hand it’s a sin of omission as my mind will eventually wonder to sinful topics if I don’t discipline it.
What do you think?

We can train ourselves not to dwell on lust and anger. Passing thoughts are not mortal sins. If we choose to entertain them, they can be.

This article (How to recognize if you have consented to temptation), published yesterday by a priest, may be helpful to you.

Full knowledge does not mean one has read the Bible several times nor does reading the Bible several times mean one as full knowledge per se (nor is the Bible meant to be a systematic theology text on moral theology).

No that does not follow. The first part is quite correct but the second part is not. No it is not true that virtually everything is. Not the case. Many things in life are good. Virtue. Many things in life are venial matter for venial sins. Many things in life are imperfections etc

It is “deliberate” consent.

Such would not really be correct - as the other two conclusions were not yet on mark. It is part what is needed to commit a mortal sin but it is not what everything hangs on.

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.

Impure thoughts are yes grave matter.

But obscene* humor *may be venial matter or serious matter- depends on what is meant- talk with your Priest. Certainly not something we should do of course even if it is venial matter. They yes should be set aside by a Christian.

If yes one consents to lustful thoughts - that would be certainly the stuff of grave sin if one had full knowledge and gave complete consent. Or leads others to sin by lustful thoughts…

As to thoughts of anger -this too can be grave matter (like hatred, desire to murder or seriously harm some one or other gravely contrary to justice or charity) or can be venial matter. Or it can even be not sinful but rather just anger.

No that is not conclusive evidence that you consent to them. And it may be an omission perhaps - but thoughts are not so easily disciplined like that. The fact that a thought happens to one does not mean one has sinned. I will post a longer post on thoughts in a moment.

What do I think? I think your seeking to follow Christ and be faithful to him but have some information that is somewhat confused here - it can be good for you t seek out a Priest who of course thinks with the Church - as a regular confessor for at least a time to work out what is sin and what is not, what is mortal what is venial, what is temptation, what is consent, what is just annoyance -etc. That can be helpful in the Spiritual Life. Many who set out on the road following him run up against some initial confusion over these things. Keep your goods desire and your eyes fixed on Christ!


All sorts of thoughts can happen to us out of the blue…

(not sought…one is not say entering into a near occasion willie nillie etc…they just happen…one does not want them…they may even be rather annoying…)

Be they impure etc

The fact that a thought happened to one- does not mean per se there was any sin.

And for mortal sin one needs not only grave matter, full knowledge and deliberate (complete) consent…

Just cause a thought happened to you does not mean there was any sin. Let alone mortal sin.

Just calmly turn to something good…


For the next few moments --try real hard NOT to think of an Apple.

then scroll down.

What did you think of?

An apple.

Even though your will was against it (you did not want to think of an apple!)

Now back to unwanted thoughts…

The more you fear and try hard not to have them…the more they will likely come and bother you.

The best thing to do with such thoughts is not to fight them directly --not fear that they will come—simply do not consent and simply and calmly turn to something else…(or it may be best to keep doing the good thing one is doing…like they come out of the blue when your at work …keep working…keep praying …etc)

It is an age old trouble that can happen - as one can find in spiritual works down through the ages.

There is a story from the desert of the early Centuries of the Church where a younger hermit when to an older one with the problems of thoughts happening to him all the time…the older hermit told him to go outside open his cloak and catch the wind.

The younger hermit said such is not possible…

the older hermit replied --neither is it possible to stop all the thoughts that can come to you…(then basically he said his task was not to consent…if they should happen…hence I would add one would turn to something else that is good…).

Ignore such unwanted thoughts like one would ignore a hissing goose or a barking dog. One does not stop to argue with a hissing goose or a barking dog does one? No one keeps on walking…

(as noted above the image there comes from a Carthusian Monk from centuries ago…)

Ignore such unwanted thoughts and do not fear them…just calmly turn to something good.

Thank you everybody for your responses. I did find them helpful.

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