Q. 1. What does the Catholic Church teach regarding an incomplete Confession? When is it necessary to return to Confession and confess one's sins that were not confessed and when is it not necessary to do so?
A. 1. The Catholic Church teaches that one must confess all his/her sins with a sincere heart (intention). Below I provide examples of when sins must be confessed versus when sins are forgiven although not confessed.
a. If you go to Confession and intentionally leave out a sin that should have been confessed, that sin is not forgiven because you did not have a sincere intention of confession the sin.
b. If you go to Confession and confess all the sins that you can remember and the priest gives you an absolution, indicating that he forgives all the sins that your remember and those you do not remember then all your sins are forgiven, even if they were not confessed.
c. You go to Confession with the intent of confessing certain sins. During your confession, the priest interrupted to ask you a number of questions. Consequently you forgot to confess one or two sins. The priest gave you the absolution after completing his question period. In such a case, the sins that you intended on confessing, they have been forgiven because you had the intent to confess them. The only reason they were not confessed is because the priest interrupted in your confession and consequently you forgot to confess that/those sins.