Christianity is a historically diverse religion, but Christians worldwide share a core set of convictions while differing in their interpretations of the Bible, sacred tradition, doctrine, and practice.^[1] Christianity includes conservative, moderate, liberal, and progressive movements of theology.^[2]

Concise doctrinal statements are known as creeds. They began as baptismal formulae and expanded during the Christological controversies of the 4th and 5th centuries into fuller statements of faith. "Jesus is Lord" is often identified as the earliest Christian creed, and the Apostles' Creed became the most widely accepted summary of Christian belief in the Western churches.^[3][4] Most Christians accept one or more historic creeds, though some Evangelical Protestants and churches in the Restoration Movement reject creeds as binding formulae even when they accept much of their substance.^[5][6][7][8]

The central tenet of Christianity is belief in Jesus as the Son of God and the Messiah (Christ). ^{[9] [10]} Christians hold that Jesus fulfilled the messianic promises of the Old Testament and that through his death and resurrection sinful humanity can be reconciled to God and offered salvation and eternal life.^[11] According to the New Testament, Jesus was conceived by the Holy Spirit, born of the Virgin Mary, preached, taught, performed miracles, was crucified, buried, and raised from the dead, then ascended to heaven and will return to fulfill the remaining divine promises.^[12][13]

Christians generally regard the death and resurrection of Jesus as the two decisive events on which Christian doctrine depends.^{[14] [15]} Christians differ, however, in how they explain the saving effect of Jesus' death. Eastern Orthodox theology emphasizes restoration and divinization, Catholic theology combines ransom and satisfaction themes, Protestant theology often emphasizes substitution, and Christian traditions differ on grace, free will, and predestination.^{[16] [17] [18] [19] [20] [21] [22]}

Christian knowing uses observation, reasoned deduction, personal experience, and grace. ^[23] Gustafson says Christian knowing assumes a condition of piety or at least a longing for piety. ^[24] He defines piety as respect awakened by dependence on powers humans do not create and cannot fully master. ^[25] He says this knowing includes data and theories about the powers that order life. ^[25] He says it also engages the affections and takes the form of gratitude. ^[26] Beckley says knowledge conditions are relative to particular communities. ^[27]

Christianity teaches that creation is good. ^[28] Christianity teaches that God is the source of all things. ^[28] Christianity teaches that God judges all things. ^[28] Christian thought treats evil as real. ^[29] Christian thought also treats suffering as real. ^[30] It does not identify all suffering with evil. ^[31] Gregg also distinguishes suffering from evil. ^[32] Weaver rejects an ontological split between self and other. ^[33] The New Testament calls believers to self-denial and service. ^[28]

Christian philosophy also produced the ontological argument for the existence of God. ^[34] This argument moves from the idea of God to the reality of God. ^[34] St. Anselm first stated it clearly in the Proslogion in 1077-78. ^[34] He defined God as "that than which nothing greater can be conceived." ^[34] He argued that such a being cannot exist only in thought. ^[34] A being that existed in reality would be greater. ^[34] Anselm therefore held that the unsurpassably perfect being must exist. ^[34] Descartes restated the argument in the Meditations in 1641. ^[34] He treated existence as an attribute that a thing can have or lack. ^[34] Most later philosophers rejected the argument because they denied that existence is a predicate. ^[34] Kant made that criticism in the Critique of Pure Reason in 1781. ^[34] Bertrand Russell later restated the objection. ^[34] He argued that existence does not add a property to a concept. ^[34] It states that the concept is instantiated. ^[34] In the 20th century Charles Hartshorne, Norman Malcolm, and Alvin Plantinga defended a second form of Anselm's argument. ^[34] They based it on "necessary existence." ^[34] Critics replied that this view confuses logical necessity with ontological necessity. ^[34] They also argued that no a priori argument can show that an ontologically necessary being is instantiated. ^[34]

A central ontological claim of mainstream Christianity is the doctrine of the Trinity. ^[35] This doctrine teaches that the one God eternally exists as three distinct persons. ^[35] These persons are the Father, the Son, and the Holy Spirit. ^[36] The doctrine describes one divine being in three persons. ^[37] The terms trias and trinitas appeared in Christian theology before the 4th century. ^[38] The triune understanding of God became normative in mainstream Christianity before and after Nicaea. ^[39]

Most major Christian traditions are Trinitarian. ^[40] Nontrinitarian movements have also existed throughout Christian history. ^[41] These movements include adoptionist, modalist, Unitarian, Restorationist, and Oneness Pentecostal groups. ^[40]

Jewish and Christian traditions long described scripture as divinely given. ^{[42] [43]} The early Church Fathers treated the scriptures as inspired, but differed on which books belonged to scripture, and later Christian traditions continued to differ over the status of the Deuterocanonical books or Apocrypha. ^[43] Roman Catholic teaching retained the formula that scripture has God as its author, but 20th-century Catholic and Protestant theology largely moved away from strict dictation and stressed the role of human authors. ^[44] Fishbane adds that divine reality is communicated through words. ^[45]

Christian teaching presents God's rule over the world and humanity through the idea of the Kingdom of God, rooted in the Old Testament and developed in the Gospels through the language of the Kingdom of God or Kingdom of Heaven. ^{[46] [47] [48]} In the Synoptic Gospels the Kingdom stands at the center of Jesus' teaching, though scholars differ sharply on whether it refers chiefly to present divine rule, a future order, or both. ^{[46] [49]}

Christian eschatology developed through different interpretations of the Kingdom. Some traditions identified it with the church, some treated it as a future apocalyptic reality, some saw it as present in Jesus' ministry, and others combined present and future in an "already and not yet" form. ^{[50] [51] [52] [53]} Christians generally believe that Christ will return, the dead will be raised, humanity will be judged, and God's kingdom will be fully established. ^{[54] [55]}

Christian teaching holds that God judges all and that the New Testament assigns this judgement to Jesus. ^{[56] [57]} The Nicene Creed and the Apostles' Creed both preserve this belief. ^[58] Gospel teaching links judgement with repentance, righteousness, and forgiveness through fellowship with Jesus. ^[59] Most Christians believe in a final judgement, and many traditions also teach an individual judgement after death. ^{[60] [61] [62] [63]}

Sin marks human life, and Christ's redemptive grace reverses its pattern. ^[64] McDermott defines original sin as an intrinsically historical dimension of life in a sinful world, in which the decisions of others shape the child's situation of freedom. ^[65] Banda says humans are dead in trespasses before Christ and cannot remove guilt or restore a saving relationship with God by their own power. ^[66] Duffy adds that Christian Scripture sets grace against sin and helplessness. ^[67] Clifford and Anatolios describe biblical models in which the human problem appears either as an unjust situation that God rectifies in history or as willful ignorance cured by saving knowledge of God through Christ. ^[68] Tracy defines salvation as freedom from a state that needs healing and freedom for a healed state. ^[69]

The proposed cure is God's saving action in Christ, not self-improvement. ^[70] McDermott presents Christ's redemptive work as God's reversal of sin and death through his Son. ^[71] Duffy defines grace as God's free gift of God's own presence and power, and as the whole sweep of God's self-communication as gift. ^[72][73] Duffy also says that humanity's present state departs from God's intention and that Christ and the Spirit free and heal. ^[72] Banda says salvation comes by grace through faith in Jesus Christ alone and is wholly an act of God. ^[74] Bâlc states that Christ "was, is and remains" the unique solution to the human problem. ^[75] Jantzen says salvation includes human wholeness and integration through relation with God. ^[76] Banda also presents a Catholic account in which Christ accomplished redemption through his death and the Eucharist carries that work forward. ^[77]

The problem of evil remains a major challenge for Christian ethics. ^[78] Calder defines evil, in the narrow sense, as the attempt or desire to inflict significant harm without moral justification by a moral agent capable of independent choice. ^[79] Christian responses include the free-will defense, soul-making theodicy, process theodicy, natural theodicy, and evolutionary theodicy. ^{[80] [81] [82] [83] [84]} Pinnock says direct contact with God does not answer Job's questions, but it makes meaning and acceptance of suffering possible. ^[85]

Some practical theologians describe the human problem less as failure to reach perfection than as suffering, weakness, brokenness, frailty, and imperfection. ^[86] In that view, the cure is not a spirituality of self-improvement but a "theology of descent" and a shift from orthodoxy to orthopathy. ^[86] This spirituality moves from possession to communion, from competition to compassion, from withdrawal to solidarity, from estrangement to engagement, and from hostility to hospitality. ^[86]

Christian morality rests on what God has done, not simply on what God has said.^[87] Christian ethical behavior is lived faith.^[87] Grace is an experienced reality of salvation in Jesus.^[88] Jesus considered his message and himself inseparable.^[89] His teaching about the kingdom of God, human behavior, and the nature of God cannot be separated from his person without losing its meaning.^[89] Jesus stands not only as a great teacher but as the mediator of salvation.^[90] Different theologies of salvation center on grace, faith, works, sacraments, and Christ's saving role.^[91] In this sense, Christian ethics is not mainly a claim that Christians possess a superior standalone moral code; as Deats's review of Gustafson summarizes, it works moral reasons, character, and action-guiding principles through religious symbols and theological concepts, and insists that beliefs about God's reality ought to have moral consequences in life.^[92]

Evidentialism says that religious beliefs are justified only if there is sufficient evidence for them, and contemporary philosophy of religion has often divided responses into two main strategies: denying that such evidence is always necessary, or arguing that sufficient evidence is in fact available.^[93] Reformed epistemology belongs to the first strategy. Plantinga argues that belief in God can be properly basic, rational, and warranted without resting on arguments or evidence in the usual sense, because it may arise from a sensus divinitatis and, in Christian belief, from the internal work of the Holy Spirit.^[94] Eh argues that, in Thomistic terms, this need not abolish evidential approaches altogether, since faith and natural theology can be treated as different but compatible responses to evidentialism.^[93]

Paul K. Moser argues that the issue is not whether Christian claims can be reduced to scientific-style proof, but whether the evidence sought is appropriate to a God worthy of worship. In his account, direct evidence of God would be more like an authorizing personal witness than a logical proof, because a personal God discloses divine reality, character, and purposes in morally transformative ways.^[95] He therefore criticizes a merely spectator model of inquiry: evidence for God is not for detached observers alone, but is meant to challenge the will toward cooperation with God's redemptive purposes.^[96] In God and Evidence, Moser adds that evidence may be volitionally sensitive, since a redemptive God would seek more than correct thinking and would call for willing response, conscience, obedience, and moral transformation.^[97] On this view, follow-worthiness cannot be judged by abstract proof alone, because Christian truth-claims present themselves together with a claim on the person.

This also sharpens criticism of systems that treat doctrine as a closed factual scheme insulated in advance from challenge. Nathan D. Shannon's analysis of Van Til argues that Christianity does not reject evidence as such, but does reject evidentialism understood as neutral reasoning from brute, uninterpreted facts.^[98] For Van Til as presented by Shannon, there are no brute facts; facts already have meaning within a wider interpretive order, and Lockean evidentialism smuggles in creaturely rational autonomy under the guise of neutrality.^[99]

The doctrines of creation, sin, salvation, and fulfillment give rise to values.^[100] These values find expression in ethical principles, codes, rules, choices, and behavior.^[100] Faith working through love states the controlling attitude of Christian moral life.^[101] Redemption and fulfillment also press human solidarity and the common good.^[102]

Grace truly transforms the human person into a new creature.^[67] The new life with God in Christ challenges Christians to live for and with God in the service of others.^[103] Christians have been justified, and they must become what they already are.^[103]

Beliefs form the way of life.^[104] The Holy Spirit regenerates believers, gives them a new nature, sanctifies them, and enables them to obey and follow God.^[66] Good work proves faith and follows faith.^[66] Zemek states that regeneration and renewal by the Holy Spirit require a life of righteousness.^[105] Christ's teaching calls for self-restraint, contempt for earthly treasures, humility, and concrete love.^[106]

Wogaman says Christian ethics must do justice to both law and grace. ^[107] He says love is, and must remain, the foundation of the Christian ethical system. ^[108] Grudem says love of neighbor is one of the two greatest commands in Christian teaching. ^[109] Grenz says this love promotes another person's good. ^[110] Hultgren says the parable of the Good Samaritan defines a neighbor as anyone who responds to those in need. ^[111] Rudman says human rights became a shared language through which Christian ethics relates law and grace to the modern world. ^[112] Hargaden says no Christian ethic can offer a consistent defense of massive wealth inequality. ^[113] Harper says sexual self-control became a central sign of choosing to follow Jesus. ^[114] Marshall says biblical law contributed ideas later adopted into modern human rights law, including due process, fairness in criminal procedure, and equity in the application of law. ^[115]

The Abrahamic religions agree that God created the universe and identify the creator with the God revealed to Abraham. ^[116] They differ, however, in how they describe God's relation to the world and to humanity. ^[117] Fishbane says Judaism's major contribution to the history of religions is the claim that divine reality is communicated through words. ^[45] Pyper says the Abrahamic traditions also contain a built-in tension between inclusivity and exclusivity. ^[118] By contrast, Raja and Rüpke say that many ancient religions focused primarily on humankind's relation to nature, and Hiebert says this focus also marked early Israel's religious landscape. ^{[119] [120]}

Judaism accepts converts but does not center its life on missionary expansion, and it teaches that non-Jews can attain righteousness by following the Noahide laws. ^[121] Maimonides wrote that "the righteous people from other nations have a place in the world to come" if they have learned what they should know about the Creator. ^[122] Jewish teaching therefore combines a covenant focused on Israel with a moral path open to the nations. ^[118]

Christianity, by contrast, encourages evangelism and missionary expansion through the Great Commission. Major churches now condemn forced conversion as sinful and contrary to human dignity, even though Christian history includes episodes in which conversion was tied to political power, conquest, or legal pressure. ^{[123] [124]}

Islam also encourages religious invitation through da'wah, which calls both Muslims and non-Muslims to understand God's commands as expressed in the Quran and Sunnah. While there were instances of forced conversion to Islam, historians describe most conversions as gradual and shaped by social, cultural, and economic influences rather than systematic coercion. ^{[125] [126]} The Quran also forbids compulsion in matters of faith. ^[127]

Secular philosophy often presses the comparison at a different point. Hickson cites Hume's formulation of the problem of evil as a major challenge to belief in a God who is both good and omnipotent. ^[29] At the same time, believers who recognize the shared figures, narratives, and Abrahamic origin of Judaism, Christianity, and Islam tend to show more positive attitudes toward other Abrahamic groups. ^{[128] [129]}

Christianity contains multiple traditions of belief and practice.^[130] These traditions include worship, rites, devotional customs, teachings of church authorities, creeds, confessions of faith, and catechisms.^[130] Catholic, Eastern Orthodox, Oriental Orthodox, and Church of the East traditions distinguish sacred tradition from ecclesial traditions.^[131] Sacred tradition transmits the Word of God handed down by the apostles.^[132] Ecclesial traditions include developments in theology, discipline, liturgy, and devotion.^[133] The church may retain, modify, or abandon ecclesial traditions.^[133] Anglican traditions uphold prima scriptura.^[134] Methodist traditions also uphold prima scriptura.^[135] This view gives Scripture primary authority.^[134] It allows tradition, reason, and experience to inform doctrine and practice in a subordinate way.^[134] Methodist teaching describes sacred tradition as the church's consensual interpretation of the Bible.^[136] Lutheran and Reformed traditions treat the Bible as the only final authority.^[135] They still use tradition in a supporting role.^[135] Many Christian bodies treat the writings of the Ante-Nicene, Nicene, and Post-Nicene Fathers as part of sacred tradition.^[137]

Christian feminism seeks to advance and understand the equality of men and women.^[138] Christian egalitarianism argues for mutual submission.^[139] Biblical patriarchy reads key Pauline texts as establishing male authority over women.^[140] Complementarianism treats women as ontologically equal and functionally different.^[141] Christian denominations and groups hold different views on homosexuality.^[142] Christian ethics contains four main views of war: pacifism, non-resistance, just war, and preventive war.^[143] The church ordained women to certain ministries until the 1200s.^[144] Most Protestant churches discourage divorce except as a last resort.^[145] They do not prohibit divorce absolutely in doctrine.^[145] Christian views on slavery began within a world that did not call for abolition.^[146] Paul offered no political program for social reform beyond the apocalyptic return of Christ.^[147]