I recently remembered a mortal sin I commited in the past
Been to confessin since this was committed? Yes? Then it has been forgiven.
I never confessed (because I forgot I did it)
We are expected to confess all mortal sins that we have
remembered at the time of confession. Those we’ve
remembered and have the intention to confess, to ask forgiveness, are forgiven. So at that time and any confession since then, if you had remembered it, you’ve would’ve confessed it- yes? Didn’t deliberately
withhold confessing the sin-no?
I know I am forgiven of it
Good!
I also know I have to confess past unconfessed sins.
True - but as it was forgiven with all the others (in the first confession after committing this sin - which you
forgot to mention at that time and in any other confession since then, but only
remembering now, so there is only the obligation to mention it at your
next confession.
Do you go to confession 2-3 weekly, or perhaps monthly? Then when you next go, make sure to mention it at this
next confession.
You can therefore be confident of being an invited guest to the banquet of the Lord - so you may
receive Holy Communion at Sunday Mass.
Edited to add link:-
What if I forgot to confess a sin and remembered it later? Was it absolved?
Baltimore Catechism Lesson 19 Q.794 "
May a person who has forgotten to tell a mortal sin in confession go to Holy Communion before
going again to confession?
A. A person who has forgotten to tell a mortal sin in confession may go to communion before again going to
confession, because the forgotten sin was forgiven with those confessed, and the confession was good and worthy."