In Catholic moral theology, a mortal sin, as distinct from a venial sin, must meet all of the following conditions:
1. its subject must be ‘grave matter’;
2. it must be committed with full knowledge, both of the sin and of the gravity of the offense;
3. it must be committed with deliberate and complete consent.
Sin is defined by St. Augustine (Contra Faustum, XXII, xxvii) as something said, done or desired contrary to the eternal law. Mortal sin specifically is further defined, as stated above (by St. Thomas Aquinas), in the Decretum Gratiani; under those circumstances the sin(s) would not be forgiven after death and would therefore lead the sinner to Hell. According to Catholic doctrine, a mortal sin produces a macula, or stain on the soul, and a person who dies in a state of mortal sin, i.e., without having repented, has thereby chosen or merited eternal separation from God in Hell. Prior to the issuance of this doctrine, it was widely believed that the presence of any unconfessed sin at time of death resulted in damnation, as evidenced in Dante’s Divine Comedy; associated with this, a valid confession could be made in articulo mortis, or at the moment of death, in which case the sinner’s soul reached Purgatory irrespective of the number and or/gravity of such sins.
Some things considered by the Magisterium of the Catholic Church to be ‘grave matters’ include adultery, murder, lust, missing mass on Sunday, perjury, incredulity, and the use of contraceptives. All of these are subject both to the conditions above and to mitigating circumstances of the individual situation, as with venial sin. The Church itself does not provide a precise list of sins, subdivided into the mortal and venial categories. Rather, it is generally considered a matter for a well-formed conscience to decide. It should not be said that missing Mass on Sunday is considered equal in gravity to murder: the Catholic belief holds that mortal sins can vary in their seriousness, although the “mortal” effect remains present for all sins in this category.
Some sins are so serious that they merit automatic excommunication from the Catholic Church. For this penalty to be imposed, one must be aware not only of the seriousness of the offense, but also of the penalty that is incurred.
Mortal sins are not to be confused with the deadly sins. The latter are categories of sin, corresponding to weaknesses in human nature, while mortal sins may also be called “grave” or “grievous” sins. They may also be referred to simply as “serious sin”.
The Catholic teaching on mortal sin was called into question by some within the Church in the late 20th century after the Second Vatican Council. In response to these doubts, Pope John Paul II reaffirmed the teaching in his encyclical Veritatis Splendor. It is maintained in the current Catechism of the Catholic Church, which says in section 1035, “Immediately after death the souls of those who die in a state of mortal sin descend into hell.”
- Catholic Encyclopedia entry on Sin
- Catechism of the Catholic Church from the official website of the Vatican