Mortal sin

A mortal sin (), 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. Three conditions must together be met for a sin to be mortal: "Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent." The sin against the Holy Ghost and the sins that cry to Heaven for vengeance are considered especially serious. 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. Teaching on absolution from serious sins has varied somewhat throughout history. The current teaching for Catholics was formalized at the 16th-century Council of Trent.
Sacred Scripture.
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 a sin that leads to death."
Fathers of the Church.
The concept is hinted at in some Fathers of the Church and explicit in others.
In AD 220, Tertullian in his "De Modestia", 21 writes,
In AD 385, Pacian of Barcelona in his "Sermon Exhorting to Penance", 4 gives contempt of God, murder, and fornication as examples of "mortal" or "capital sins."
In AD 393, St. Jerome writes "Against Jovinian", 2:30:
Roman Catholicism.
In Roman Catholic moral theology, a mortal sin requires that all of the following conditions are met:
The "Catechism of the Catholic Church" defines "grave matter":
1858. Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: "Do not murder, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother." The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.
This would include worshiping other gods and blasphemy. Although the Church itself does not provide a precise list of grave sins or divide actions into grave and venial categories, Church documents do name certain "grave sins" as well as "offenses" and "actions" whose subject-matter is considered to be grave. For example, in the area of human sexuality, the Catechism of the Catholic Church notes that the following actions can involve increased gravity: extramarital sex, divorce (but not legitimate separation), and masturbation. The sins against the Holy Ghost and the sins that cry to Heaven for vengeance are considered especially serious.
With respect to a person's full knowledge of a certain act being a grave sin, the Catholic Church teaches that "unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders (mental illness). Sin committed through malice, by deliberate choice of evil, is the gravest." Furthermore, Catholic teaching also holds that "imputability and responsibility for an action can be diminished or even nullified by ignorance, inadvertence, duress, fear, habit, inordinate attachments, and other psychological or social factors." In this regard, a sin committed while one is inebriated may lack the awareness and consent necessary for the sin to be mortal. But when one becomes aware of the danger of excessive drink, such drinking itself becomes a serious matter.
Grave sins should not to be confused with the seven deadly sins, which are so called because they lead to other sins; they are not necessarily grave sins.
Mortal sins are called "grave sins" under the Code of Canon Law due to the "grave" nature of all mortal sins, and the terms are used there interchangeably. This does not deny the distinction given above, that there may be grave "matter" but not a grave "sin" if the other conditions of knowledge and freedom are not present.
Mortal sins must be confessed by naming the specific offence along with how many times it was committed. Mention of how long since one's last confession is to establish whether one is truly penitent – has a purpose of amendment.
It is not necessary to confess venial sins although they may be confessed, a practice that began with the Irish monks around the 12th century. Venial sins are all sins that are not mortal. The Church encourages frequent, intelligent use of the sacrament of confession even if a person has only venial sins, in view of the benefits that might be derived.
According to the Catholic Church, no person can receive the Eucharist when in a state of mortal sin:
Some mortal sins cause automatic excommunication by the very deed itself, for example renunciation of faith and religion, known as apostasy, desecration of the Eucharistic species, and "a completed abortion". Those mortal sins are so serious that the Church through law has made them crimes. The Church forbids the excommunicated from receiving any sacrament (not just the Eucharist) and also severely restricts the person's participation in other Church liturgical acts and offices. A repentant excommunicated person may talk to a priest, usually in a confessional, about their excommunication to arrange for the remission. Remission cannot be denied to someone who has truly repented their actions and has also made suitable reparation for damages and scandal or at least has seriously promised to do so. However, even if excommunicated, a Catholic who has not been juridically absolved is still, due to the irrevocable nature of baptism, a member of the Catholic Church and therefore must still carry out their obligations of fulfilling their duties of attending Mass, Divine Liturgy, etc. on a Holy Day of Obligation, abstaining from meat on the Fridays of Lent, etc., albeit their communion with the Christ and the Church is gravely impaired. "Perpetual penalties cannot be imposed or declared by decree." However, "the following are expiatory penalties which can affect an offender either perpetually..."
Since the mid-twentieth century, some theologians have taught that a person who lives by a constant attitude of charity is unlikely to fall in and out of God's graces without being profoundly aware of the change. The term "fundamental option" arose and is used in a variety of senses.
Pope John Paul II reaffirmed traditional teaching going back to the Council of Trent in his encyclical "Veritatis Splendor," as does the "Catechism of the Catholic Church", which states: "The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, 'eternal fire'." The Catechism then adds: "The chief punishment of hell is eternal separation from God, in whom alone man can possess the life and happiness for which he was created and for which he longs." However, the Catechism does not by name say a specific person is in Hell, but it does say that "...our freedom has the power to make choices for ever, with no turning back." Most significantly, the Catechism also proclaims that "There are no limits to the mercy of God..." and that "although we can judge that an act is in itself a grave offence, we must entrust judgment of persons to the justice and mercy of God." We cannot see into their mind to know if it was deliberate or committed in full knowledge. Also, like the father in the Parable of the Prodigal Son, God forgives those who repent sincerely. Vatican II, in its Dogmatic Constitution "Lumen Gentium", reflects the traditional teaching of the Church on punishment, and on merit or reward for good deeds.
Mortal Sin is ordinarily remitted by the priestly absolution in the Sacrament of Penance. However, the effectiveness of the absolution is dependent of the acts of the penitent starting with sorrow for sin or contrition. Perfect contrition (or imperfect contrition, also called attrition, in the Sacrament of Penance), coupled with the firm resolution to sin no more and to make recourse to the sacrament of Penance as soon as possible, can restore a person's relationship with God, as well as God's saving grace, that is, sanctifying grace. This teaching on perfect contrition is a reminder that God's mercy and forgiveness is available outside the Sacrament of Penance, yet, also indicates that Catholics who know about Christ's institution of the sacrament of Penance must intend to use it. Any human act that arises from a person's love of God, is inspired by God's prevenient action and is directed to doing as God requires. 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.
Eastern Catholic churches.
Eastern Catholic churches (autonomous, self-governing [in Latin, "sui iuris"] particular churches in full communion with the Bishop of Rome, the Pope), which derive their theology and spirituality from some of the same sources as the Eastern Orthodox and Oriental Orthodox, use the Latin Catholic distinction between "mortal" and "venial" sin, 
Actions constituting grave matter.
The following is a partial list of actions that are defined as constituting grave matter, according to the "Catechism of the Catholic Church" or like sources (such as declarations by the Congregation for the Doctrine of the Faith, Apostolic Letters, or other sources printed by Church authorities).
Eastern Orthodoxy.
According to Fr. Allyne Smith, "While the Roman Catholic tradition has identified particular acts as 'mortal' sins, in the Orthodox tradition we see that only a sin for which we don't repent is 'mortal.'"
In the Orthodox Church there are no "categories" of sin as found in the Christian West. In the pre-Vatican II Catholic catechism, sins were categorized as "mortal" and "venial." In this definition, a "mortal" sin was one which would prevent someone from entering heaven unless one confessed it before death. ...These categories do not exist in the Orthodox Church. Sin is sin. Concerning Confession, having a list of deadly sins could, in fact, become an obstacle to genuine repentance. For example, imagine that you commit a sin. You look on the list and do not find it listed. It would be very easy to take the attitude that, since it is not on a list of deadly sins, it is not too serious. Hence, you do not feel the need to seek God's forgiveness right away. A week passes and you have completely forgotten about what you had done. You never sought God's forgiveness; as a result, you did not receive it, either. We should go to Confession when we sin – at the very least, we should ask God to forgive us daily in our personal prayers. We should not see Confession as a time to confess only those sins which may be found on a list.
Though not part of the dogma of the Orthodox Church the mortal/venial distinction is assumed by some Orthodox authors and saints as a theologoumenon. For example, Saint Ignatius Brianchaninov (1807–1867), who wrote primarily for monks, in his book "A Word on Death", in a chapter entitled "Mortal sin", says:
Similarly, the "Exomologetarion" of Nicodemus the Hagiorite (1749–1809) distinguishes seven classes of sin:
Nicodemus gives the following example for the seven classes of sin. "The initial movement of anger is pardonable; near to the pardonable is for someone to say harsh words and get hot-tempered. A non-mortal sin is to swear; near the non-mortal is for someone to strike with the hand. Between the non-mortal and the mortal is to strike with a small stick; near the mortal is to strike with a large stick, or with a knife, but not in the area of the head. A mortal sin is to murder. A similar pattern applies to the other sins. Wherefore, those sins nearer to the pardonable end are penanced lighter, while those nearer to the mortal end are more severely penanced."
He also stipulates seven conditions of sin: