Can you sin and not know it?


Hi there,

I am sure this question has been asked before but I couldn’t find it asked recently.

Can you sin–venial or mortal–and not be aware of it? Or is all sin intentional?

The Jesus prayer: “Lord Jesus Christ, son of God, have mercy on me a sinner” seems to suggest to me that you can sin without realising it - because then why would so many pray the Jesus prayer often and then go around intentionally sinning? Surely they must be referring most of the time to unintentional sins?

Thank you,


My opinion is that you surely can sin.
For the sin to be mortal though, you need full consent, which would be odd to give without knowing ou are doing what you are doing, and knowing about the gravity of the act. This also would be funny, if you didn’t know that you are sinning, but for this sin to me mortal you have to know it is a grave one…

So the distinction on sin is not if we know or not - see natural law - but if we freely consent and know about the sinfulness of it.

About the prayer, it refers also to concupiscence, which is a result of original sin. In that sense, we all are sinners, we are all fallen from grace.


Thank you MarcoPG. I’m not sure I fully understand however in regards to venial sins.
Can we commit venial sins and not know it?


Yes. YOu may do something sinful, which goes against natural or moral law, and you woudn’t even feel guilty about it. But it is a sin anyway. Take for instance lying. Also, every sin that you didnÄt know was one at the moment you committed it, is a sin anyway.


You cannot do a mortal sin without know.


It would be a material sin, but not a formal sin. In the context of the OP’s question, no this would not be a sin (not a sin the person is culpable for).


Sin is always intentional, it is a choice. So in a strict sense, a person must know something to be wrong and to choose it.

Less strictly, I would say we commit minor venial sins all the time by choosing something wrong in minor and fleeting ways. As such, these minor and fleeting choices can pass so quickly as to escape our consciousness and memory as though we never made the choice. In that sense, we could say that we sin without really knowing it.


Sin is committed in the will, not the intellect (though a willfully evil choice can certainly be conceived by a neglected or poorly formed intellect). Therefore, it is possible for one in ignorance to commit an act of intrinsic evil without also committing a sin.


I don’t believe that some n is always intentional. I’m sure there could be times that someone sins and they may not even be fully aware.


One need not be “fully aware” perhaps; there can be levels of awareness and thus differing culpability. But sin is always defined by a choice of the will. It is a deliberate decision to do something one knows to be wrong. No, one cannot sin without being aware of it - at least for the fleeting moment in which one makes the particular choice. And the awareness could perhaps fade as quickly too, so that soon after making the wrong choice one has lost awareness of having made it.


The Catechism of the Catholic Church shows that the moral sense exists in the conscience and that ignoring it makes it more willful.
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 133 do not diminish, but rather increase, the voluntary character of a sin.
1860 Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.
1865 Sin creates a proclivity to sin; it engenders vice by repetition of the same acts. This results in perverse inclinations which cloud conscience and corrupt the concrete judgment of good and evil. Thus sin tends to reproduce itself and reinforce itself, but it cannot destroy the moral sense at its root.


Yes, you can sin without knowing it. Objectively sinful acts or omissions are still sins, whether you know it or not (invincible ignorance.) After all, it is written that 'The just man sins seven times a day." That said, God does not expect the impossible - just as with children below the age of reason, if one truly doesn’t know something is a sin, it is not held against him/her.


Sins of omission can be with knowledge. I chose to omit my responsibilities to my family in any number of ways. I know this. It is a sin of omission thru laziness or selfishness. And I know that it is a sin. But there are other kinds of sins of ommission without my knowledge or awareness of them.

I may not see the sin in my neglect of my responsibilities.

A parent has the responsibility to raise their child in the love and knowledge of God.
Yet the parents do not set the example. And maybe all they confess is that they missed Mass on Sundays, yet they didn’t see to it that their children were given good example nor were the children given proper instruction in the faith. These sins are not confessed and not seen. But they are real sins just the same…scandal to and neglect of their children. (I know, there may be exceptions…there always is.)


Luke 12:48
But he that knew not, and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more.

In the words of Jesus, yes we can commit sins unknowingly and still be held accountable. This is why the Catholic Church also teaches about culpability.


Thank you everyone for your good responses - this has helped me understand the issue more.

I have a friend who says we cannot sin and be unaware of it. He cites the power of baptism (old man gone, new man has come) and prophecies in the Old Testament saying how we will receive a new heart and the law of God will be written on our hearts to prove his point. For him this means that because the law of God is written on our hearts and we are a new man we should be aware of all occasions of sin, mortal and venial.

How does one respond to this?


Not by opposing it completely, as he is probably referring to natural law. So by this priniple, you may not pay attention to the gravity because you weren’t educated in the proper way to see the gravity of an action, but you feel something is wrong, either within you or outside of you.
And it is true, by reasoning on natural moral law, one should come to the conclusions we come to concerning good and bad. Still, even after that, you may be aware of the gravity but do it anyway. That’s is often where the sin becomes mortal, because many times we know deep inside that we are doing something wrong but out of pleasure, pride, or other vain things, we do it anyway.
So a new heart doesn’t make you a puppet nor a care bear. :slight_smile:


The Catholic teaching is different. We receive actual graces of God to help us to conversion, and we have a conscience from birth, all before baptism.

At Baptism we receive Sanctifying Grace with an indelible character, the theological virtues of faith, hope, and charity, and the seven forms of supernatural instincts that, with full consent, answer divine impulses of grace: wisdom, understanding, knowledge, fortitude, counsel, piety, and fear of the Lord.

*] “Know you not that you are the temple of God, and that the Spirit of God dwelleth in you?” (I Corinthians 3, 16).
*]“If anyone love Me he will keep My word; and My Father will love him, and We will come to him, and will make Our abode with him.” (John 14, 23).

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