So if you think or judge that something is a venial sin when you do an act, but you find out later that what you did is grave matter, did you commit a venial sin or a mortal sin?
did you fulfill the conditions?
It must be committed with full knowledge, both of the sin and of the gravity of the offense;
you did not know the gravity of offence, so you did a venial sin.
But, now you know. Inform your conscience so that you do not commit the same sin again. Next time you will know the gravity of the sin!
Also, you should ask yourself why you decided to go ahead and do it, knowing it was sinful? I understand you thought it was “only” venial, but still.
Since we have answered the question of the op, let us now refrain from posting here in accordance with forum rules.
Maybe I’m a little slow… what rule are you referring to?
Messages posted to threads should be on-topic. If you wish to discuss another topic, start a new thread.
It is certainly good to reassure the OP that in our opinions mortal sin did not occur, but it is even more important that it not occur in the future. Repeating the sin having full knowledge of its gravity would be grievous. We responded with charity to ensure that this doesn’t happen. This certainly does not rise to the level of the prohibition you have suggested. :shrug: