I’ve heard it on these forums before that one should confess ALL sin because one doesn’t know for sure if a sin truly is only venial instead of mortal.
Does the Church teach that one can’t definitively distinguish a venial sin from a mortal sin?
If so, where does it say that?
The closest I could find is the Baltimore Catechism saying it is good to confess venial sins become Sometimes it’s hard to distinguish, not all the time.
I’m not sure how one could entertain the possibility they committed a mortal sin if they are consciously aware of only semi-deliberately saying an idle word.