In Christianity, sin is an immoral act and transgression of divine law. The doctrine of sin is central to the Christian faith, since its basic message is about redemption in Christ.
Hamartiology, a branch of Christian theology which is the study of sin, describes sin as an act of offence against God by despising his persons and Christian biblical law, and by injuring others. Christian hamartiology is closely related to concepts of natural law, moral theology and Christian ethics.
In Christianity, Jesus is the Son of God as chronicled in the Bible's New Testament, as well as prophesied in the Old Testament, and is held to be God the Son, a prosopon (Person) of the Trinity of God. Christians believe him to be the Jewish messiah (giving him the title Christ), who was prophesied in the Bible's Old Testament. Through Jesus's crucifixion and resurrection, Christians believe that God offers humans salvation and eternal life, with Jesus's death atoning for all sin.
These teachings emphasize that as the Lamb of God, Jesus chose to suffer nailed to the cross at Calvary as a sign of his obedience to the will of God, as an "agent and servant of God". Jesus's choice positions him as a man of obedience, in contrast to Adam's disobedience. According to the New Testament, after God raised him from the dead, Jesus ascended to heaven to sit at the right hand of God the Father, with his followers awaiting his return to Earth and God's subsequent Last Judgement.
In Christianity, salvation (also called deliverance or redemption) is the saving of human beings from sin and its consequences—which include death and separation from God—by Christ's death and resurrection, and the justification entailed by this salvation.
The idea of Jesus's death as an atonement for human sin was recorded in the Christian Bible, and was elaborated in Paul's epistles and in the Gospels. Paul saw the faithful redeemed by participation in Jesus's death and rising. Early Christians regarded themselves as partaking in a new covenant with God, open to both Jews and Gentiles, through the sacrificial death and subsequent exaltation of Jesus Christ.
In Western Christian beliefs, grace is God's favor, and a "share in the divine life of God". It is a spontaneous gift from God – "generous, free and totally unexpected and undeserved" – that cannot be earned. In the Eastern Orthodox Church, grace is the uncreated energies of God. Among Eastern Christians generally, grace is considered to be the partaking of the divine nature described in 2 Peter 1:4 and grace is the working of God himself, not a created substance of any kind that can be treated like a commodity.
As an attribute of God, grace manifests most in the salvation of sinners, and Western Christianity holds that the initiative in the relationship of grace between God and an individual is always on the side of God.
The Ninety-five Theses or Disputation on the Power and Efficacy of Indulgences is a list of propositions for an academic disputation written in 1517 by Martin Luther, then a professor of moral theology at the University of Wittenberg, Germany. The Theses are retrospectively considered to have launched the Protestant Reformation and the birth of Protestantism, despite various quasi- or proto-Protestant groups having existed previously.
The Theses are framed as propositions to be argued in an academic debate rather than necessarily representing Luther's opinions. They aired contemporary theological misgivings about the theory and practice of indulgences and their relation to repentance, penance and papal authority: this was triggered by the scandal of certain Catholic clergy, who were supposedly selling plenary indulgences in Germany, which were certificates supposed to reduce the temporal punishment in purgatory for sins committed by the saved purchasers or their loved ones.
Repentance (a term related to Greek: μετάνοια, romanized: metanoia), in Christianity, refers to being sorrowful for having committed sin and then turning away from sin toward a life of holiness.
In certain Christian traditions, such as Catholic theology, Lutheran theology, Orthodox theology and Anglican theology, repentance plays a key role in confession and absolution. It can specifically refer to a stage in Christian salvation in which an individual gains awareness of God's standard, acknowledges their past or present wrongdoings, and deliberately turns away from sin toward God; its numeration as a stage in the ordo salutis varies with the Christian denomination, with the Reformed theological tradition arguing it occurs after faith. Christian denominations that adhere to the liturgical kalendar, such as Catholicism, Lutheranism, Moravianism and Anglicanism, focus on repentance during the season of Lent, while emphasizing its importance in the life of the believer throughout the year.
Papal infallibility is a dogma of the Catholic Church (both the Latin and Eastern Catholic churches) which states that, in virtue of the promise of Jesus to Peter, the Pope when he speaks ex cathedra is preserved from the possibility of error on doctrine "initially given to the apostolic Church and handed down in Scripture and tradition". It does not mean that the pope cannot sin or otherwise err in many cases. This doctrine, defined dogmatically at the First Vatican Council of 1869–1870 in the document Pastor aeternus, is claimed to have existed in medieval theology and to have been the majority opinion at the time of the Counter-Reformation.
The doctrine of infallibility relies on one of the cornerstones of Catholic dogma, that of papal supremacy, whereby the authority of the pope is the ruling agent as to what are accepted as formal beliefs in the Catholic Church. The use of this power is referred to as speaking ex cathedra. "Any doctrine 'of faith or morals' issued by the pope in his capacity as successor to St. Peter, speaking as pastor and teacher of the Church Universal [Ecclesia Catholica], from the seat of his episcopal authority in Rome, and meant to be believed 'by the universal church,' has the special status of an ex cathedra statement. Vatican Council I in 1870 declared that any such ex cathedra doctrines have the character of infallibility (session 4, Constitution on the Church 4)."
In Christian theology, a mortal sin (Latin: peccātum mortāle) is a gravely sinful act which can lead to damnation if a person does not repent of the sin before death. It is alternatively called deadly, grave, and serious; the concept of mortal sin is found in both Catholicism and Lutheranism. 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 Spirit and the sins that cry to Heaven for vengeance are considered especially serious. This type of sin is distinguished from a venial sin in that the latter 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 sins is varied somewhat throughout Christian denominations. The teaching for Catholics on the sacrament of confession and the act of contrition for absolution was declared a mandatory catholic belief in the Council of Trent. Confession and Absolution is practiced in Lutheran churches, with it being historically held on Saturdays in preparation for Mass on the Lord's Day (Sunday).