what is mortal sin in the catholic church
Mortal sin A mortal sin (Latin: peccatum mortale), in Catholic theology, is a gravely sinful act, which can lead to damnation if a person does not repent of the sin before death. A sin is considered to be "mortal" when its quality is such that it leads to a separation of that person from God's saving grace. This type of sin should be distinguished from a venial sin that simply leads to a weakening of a person's relationship with God. Despite its gravity, a person can repent of having committed a mortal sin. Such repentance is the primary requisite for forgiveness and absolution.[1] Teaching on absolution from serious sins has varied somewhat throughout history. The current Catholic teaching was formalized at the 16th century Council of Trent.
Papal infallibility Papal infallibility is a dogma of the Catholic Church that states that, in virtue of the promise of Jesus to Peter, the Pope is preserved from the possibility of error "when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority, he defines a doctrine concerning faith or morals to be held by the whole Church."[1][2]