Sin

===Hamartiology===
{{Main|Christian views on sin}}
{{See also|Seven deadly sins}}
The doctrine of sin is central to Christianity, since its [[The gospel|basic message]] is about [[redemption (theology)|redemption]] in [[Jesus in Christianity|Christ]].<ref>Rahner, p. 1588</ref> [[Christianity|Christian]] [[hamartiology]] describes sin as an act of offense against [[God in Christianity|God]] by despising his [[Trinity|persons]] and [[Biblical law in Christianity|Christian biblical law]], and by injuring others.<ref>Sabourin, p. 696</ref> In Christian views it is an [[evil]] human act, which violates the rational nature of man as well as [[Trinity|God's nature]] and his [[eternal law]]. According to the classical definition of [[Augustine of Hippo|St. Augustine of Hippo]] sin is "a word, deed, or desire in opposition to the eternal law of God."<ref>''Contra Faustum Manichaeum'', 22, 27; [[Patrologia Latina|PL]] 42, 418; cf. [[Thomas Aquinas]], [[Summa Theologica|STh]] I–II q71 a6.</ref><ref>Mc Guinness, p. 241</ref> Thus, sin requires redemption, a metaphor alluding to atonement, in which the death of Jesus is the price that is paid to release the faithful from the bondage of sin.<ref>Gruden, Wayne. Systemic Theology: An Introduction to Biblical Doctrine, Nottingham: Intervarsity Press, p. 580</ref> In some forms of Christianity, it also requires reparation (see [[penance]]).

Among some scholars, sin is understood mostly as a legal infraction or contract violation of non-binding philosophical frameworks and perspectives of [[Christian ethics]], and so [[Salvation in Christianity|salvation]] tends to be viewed in legal terms. Other Christian scholars understand sin to be fundamentally relational—a loss of love for the [[God in Christianity|Christian God]] and an elevation of [[self-love]] ("concupiscence", in this sense), as was later propounded by Augustine in his debate with the [[Pelagianism|Pelagians]].<ref>''On Grace and Free Will'' (see ''Nicene and Post-Nicene Fathers'', trans. P.Holmes, vol. 5; 30–31 [14–15]).</ref> As with the legal definition of sin, this definition also affects the understanding of [[Grace in Christianity|Christian grace]] and salvation, which are thus viewed in relational terms.<ref>For a historical review of this understanding, see R.N.Frost, "Sin and Grace", in Paul L. Metzger, ''Trinitarian Soundings'', T&T Clark, 2005.</ref>