When do thoughts become sin?


When does an evil thought become a mortal sin?

I recently heard of a couple delaying the baptism of an infant because thay want a particular priest to perform the ceremony, and I remember thinking “what if the baby dies before it’s baptized?”

Then “wouldn’t that serve them right for delaying the baptism?”

Then “how could you think such a thing?”

And then (worst of all) “why shouldn’t they suffer the way you have”?

Did I commit a mortal sin (in my mind)?

When do unwanted thoughts become sin?

When does a particularly evil thought become a mortal sin?

I’ve heard it said that a thought becomes a sin when you entertain it, but I’m not sure what that means, or how to tell whether I did it.

I’ve thought about this for over a week now, so it must have got my attention, but I hope entertaining a thought means more than just giving it attention.

Can anyone help me?


**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.


Catechism: scborromeo.org/ccc/p3s1c1a8.htm#IV


Your confessor can help one judge if need be. But as I noted above for a mortal sin one needs not only a grave matter but full knowledge and deliberate consent. Complete consent.

All sorts of thoughts can “happen to us” out of the blue - that we do not consent to -that just happen and we either answer - or often which is best -we turn away from and towards something else.

This can be helpful from Jimmy Akin Senior Apologist of Catholic Answers:



And since you mention “unwanted thoughts” I will re-post an older post of mine.

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

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

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

(And some need some medical/professional assistance in this area…such as medication etc and often a regular confessor )


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 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 …etc)

(one can gently - *conversi ad Dominum *- turn towards the Lord -perhaps with a look of love or a short prayer which is a very ancient practice - pm me if you if you need more).

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…and at most laughs at them…

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


I think we spend too much time trying to minimize our sins and the fact that we all sin… a lot. We should be more accepting of the fact that we all sin. Really doesn’t matter the ‘level’ of sin we commit. Sin is sin, and the only one that can forgive us of them is God/Jesus Christ.

Matthew 5:28

But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.



Yes it very much matters. Yes one seeks to avoid all sin and of course repent of all sin. it is not minimizing sin to examine oneself and know what ones sins are and to repent accordingly.

Jesus came so we may be forgiven and know true life in him.


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