What is a mortal sin?
A mortal sin has 3 qualities.
1. Grave matter: the act or omission must be serious matter. A violation of the ten commandments is considered to be grave matter. The grey area is when does stealing become a mortal sin, or gossip against one's neighbor. I will treat these specific questions in later posts.
2. Knowledge: the person must know that the action is grave matter. A person's ignorance can lessen his or her guilt.
3. Freedom: the person must freely choose to commit the gravely wrong act. If someone is coerced to do something this lessens their guilt. If the coercion is very strong the person might have no guilt at all. A child is not responsible for misding mass on Sunday if his parents fail to take him. The child has no freedom in the matter.