Mortal sin

A mortal sin (Latin: peccata mortalia), in Catholic theology, is a gravely wrongful act, which can lead to eternal damnation, if a person is not absolved 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 leads to a weakening of a person's relationship with God, as well as from an "eternal sin" that (by its very nature) cannot be repented. Despite its gravity, a person can repent of having committed a mortal sin. Such repentance can, in turn, enable a person to obtain absolution.

According to Catholic teaching, imperfect contrition, coupled with a firm resolution to sin no more, can restore a person's relationship with God, as well as God's saving grace. Under ordinary circumstances this takes place through absolution, which is received during the Sacrament of Penance. However, as God's mercy and forgiveness is not bound by the Sacrament of Penance, under extraordinary circumstances a mortal sin can be remitted through perfect contrition, which is a human act that arises from a person's love of God. When perfect contrition is the means by which one seeks to restore one's relationship with God, there must also be a resolution to confess all mortal sins (that have not been confessed and absolved previously) in the Sacrament of Penance. A resolution to confess these sins, as soon as possible, should be made with an act of perfect contrition, regardless of whether or not a person believes that they will have access to the Sacrament of Penance.

The term "mortal sin" is thought to be derived from the New Testament of the Bible. Specifically, it has been suggested that the term comes from the 1 John 5:16-17. In this particular verse, the author of the Epistle writes "there is such a thing as deadly sin."

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