internal acts

What is an internal act? In my view an internal act is a thought though I’ve never heard this particular phrase before to my knowledge. In another thread it is mentioned that an internal act is a sin. I’ve read many times on caf that thoughts are not sins. Thoughts come and go.
So can a thought be a sin if we don’t let it go but entertain it for a while and become attached to it? Is this what might be meant by an internal act?
I’ve started this thread so as not to derail another any more than I may have already with a question that didn’t really pertain to the original post.
Thank you for any help with this question.

Can thoughts be sins?

Yes most certainly.

Compendium issued by Pope Benedict XVI

393. Is there a variety of sins?


There are a great many kinds of sins. They can be distinguished according to their object or according to the virtues or commandments which they violate. They can directly concern God, neighbor, or ourselves. They can also be divided into sins of** thought**, of word, of deed, or of omission.

Does that mean all thoughts that “happen” to one with sinful content = a committed sin?

No. (see my post “unwanted thoughts” that I have posted so many times).

Sin involves knowledge and consent.

Thank you Bookcat for clearing this up about thoughts and sins. So are thoughts the internal acts you were referring to in the other thread?


One can add (which can really still be in the realm of thoughts) desires, imaginings…

Or say looking and seeking sexual pleasure (or consenting to it -if it happens)…etc

That sort of thing.

Point being was that sins are not only referring to external acts.

Once again Thank you. You’ve been quite helpful.

Your welcome.

One could add other aspects too …other “internal sins” …(which indeed can be included under sins of thought).

such as embracing sinful attitude. an erroneous belief etc.

Internally agreeing with an sinful way of living…approving …etc etc.

(even though one has not expressed it externally).

Again all involving* knowledge and consent.*


1853 Sins can be distinguished according to their objects, as can every human act; or according to the virtues they oppose, by excess or defect; or according to the commandments they violate. They can also be classed according to whether they concern God, neighbor, or oneself; they can be divided into spiritual and carnal sins, or again as sins in thought, word, deed, or omission. The root of sin is in the heart of man, in his free will, according to the teaching of the Lord: "For out of the heart come evil thoughts, murder, adultery, fornication, theft, false witness, slander. These are what defile a man."128 But in the heart also resides charity, the source of the good and pure works, which sin wounds.

128: Mt 15:19-20.

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