Does Mental Illness Affect Culpability?
Are mortal sins that are committed while mentally ill required to be dealt with by confession? What if the mental illness is serious and the individual can lead a normal life but at times falls apart?
One of the requirements to be culpable of a mortal sin is that the person needs to have known the seriousness of the sin and freely chosen to commit it. Someone with mental illness may have a diminished capacity to understand or freely choose. However, that does not mean he is devoid of all freedom and understanding, and therefore confession may be entirely appropriate in some situations.
Guidelines for the Celebration of the Sacraments with Persons with Disabilities:
28. Only those who have the use of reason are capable of committing serious sin. Nevertheless, even young children and persons with mental disabilities often are conscious of committing acts that are sinful to some degree and may experience a sense of guilt and sorrow. As long as the individual is capable of having a sense of contrition for having committed sin, even if he or she cannot describe the sin precisely in words, the person may receive sacramental absolution. Those with profound mental disabilities, who cannot experience even minimal contrition, may be invited to participate in penitential services with the rest of the community to the extent of their ability.
29. In the case of individuals with poor communication skills, sorrow for sin is to be accepted even if this repentance is expressed through some gesture rather than verbally . . .