From The Art and Popular Culture Encyclopedia
Mortal sin, according to the beliefs of Roman Catholicism, is a sin that, unless confessed and absolved (or at least sacramental confession is willed if not available), condemns a person's soul to Hell after death. But even so, you cannot go to heaven if the sin is of a serious enough magnitude. The phrase is used in I John 5.16 -17: "If you see your brother or sister committing what is not a mortal sin, you will ask, and God will give life to such a one - to those whose sin is not mortal. There is sin that is mortal; I do not say you should pray about that. All wrongdoing is sin, but there is sin that is not mortal." (NRSV)
- its subject must be a grave (or serious) matter;
- it must be committed with full knowledge, both of the sin and of the gravity of the offense;
- it must be committed with deliberate and complete consent.