Church (congregation) in the context of "Christian ecumenism"

A church, church building, or chapel is a building used for Christian worship services and Christian activities. The earliest identified Christian church is a house church founded between 233 AD and 256 AD. The word church also describes a body or assembly of Christian believers, while "the Church" refers to the worldwide Christian religious community.

In traditional Christian architecture, the plan view of a church often forms a Christian cross. The center aisle and seating create the vertical beam, while the bema and altar form the horizontal arms. Towers or domes rise above the heaven-facing roof line to encourage contemplation of the divine. Modern churches employ varied architectural styles, and many buildings originally designed for other purposes have been converted to churches. From the 11th to the 14th centuries, Western Europe experienced a wave of church construction.

A Christian denomination is a distinct religious body within Christianity that comprises all church congregations of the same kind, identifiable by traits such as a name, particular history, organization, leadership, theological doctrine, worship style and, sometimes, a founder. It is a secular and neutral term, generally used to denote any established Christian church. Unlike a cult or sect, a denomination is usually seen as part of the Christian religious mainstream. Most Christian denominations refer to themselves as churches, whereas some newer ones tend to interchangeably use the terms churches, assemblies, fellowships, etc. Divisions between one group and another are defined by authority and doctrine; issues such as the nature of Jesus, the authority of apostolic succession, biblical hermeneutics, theology, ecclesiology, eschatology, and papal primacy may separate one denomination from another. Groups of denominations—often sharing broadly similar beliefs, practices, and historical ties—are sometimes known as "branches of Christianity". These branches differ in many ways, especially through differences in practices and belief.

Individual denominations vary widely in the degree to which they recognize one another. Several groups say they are the direct and sole authentic successor of the church founded by Jesus Christ in the 1st century AD. Others, however, believe in denominationalism, where some or all Christian groups are legitimate churches of the same religion regardless of their distinguishing labels, beliefs, and practices. Because of this concept, some Christian bodies reject the term "denomination" to describe themselves, to avoid implying equivalence with other churches or denominations.

In Christian theology, ecclesiology is the study of the Church, the origins of Christianity, its relationship to Jesus, its role in salvation, its polity, its discipline, its eschatology, and its leadership.

In its early history, one of the Church's primary ecclesiological issues had to do with the status of Gentile members in what had become the New Testament fulfilment of the essentially Jewish Old Testament church. It later contended with such questions as whether it was to be governed by a council of presbyters or a single bishop, how much authority the bishop of Rome had over other major bishops, the role of the Church in the world, whether salvation was possible outside of the institution of the Church, the relationship between the Church and the State, and questions of theology and liturgy and other issues. Ecclesiology may be used in the specific sense of a particular church or denomination's character, self-described or otherwise. This is the sense of the word in such phrases as Catholic ecclesiology, Protestant ecclesiology, and ecumenical ecclesiology.

A church service (or a worship service) is a formalized period of Christian communal worship, often held in a church building. Most Christian denominations hold church services on the Lord's Day (offering Sunday morning and Sunday evening services); a number of traditions have mid-week services, while some traditions worship on a Saturday. In some Christian denominations, church services are held daily, with these including those in which the seven canonical hours are prayed, as well as the offering of the Mass, among other forms of worship. In addition to this, many Christians attend services on holy days such as Christmas, Ash Wednesday, Good Friday, Ascension Thursday, among others depending on the Christian denomination.

The church service is the gathering together of Christians to be taught the "Word of God" (the Christian Bible) and encouraged in their faith. Technically, the church in "church service" refers to the gathering of the faithful rather than to the physical place in which it takes place. In most Christian traditions services are presided over by clergy wherever possible, but some traditions utilize lay preachers. Styles of service vary greatly, from the Catholic, Lutheran, Eastern Orthodox, Oriental Orthodox, Reformed (Continental Reformed, Presbyterian and Congregationalist) and Anglican traditions of liturgical worship to informal worship characterized by certain free church traditions, common among Methodists and Baptists, that often combine worship with teaching for the believers, which may also have an evangelistic component appealing to backsliders and the non-Christians in the congregation (cf. altar call). Quakers and some other groups have no formal outline to their services, but allow the worship to develop as the participants present feel moved.

A sermon is a religious discourse or oration by a preacher, usually a member of clergy. Sermons address a scriptural, theological, or moral topic, usually expounding on a type of belief, law, or behavior within both past and present contexts. Elements of the sermon often include exposition, exhortation, and practical application. The act of delivering a sermon is called preaching. In secular usage, the word sermon may refer, often disparagingly, to a lecture on morals.

In Christian practice, a sermon is usually preached to a congregation in a place of worship, either from an elevated architectural feature, known as a pulpit or an ambo, or from behind a lectern. The word sermon comes from a Middle English word which was derived from Old French, which in turn originates from the Latin word sermō meaning 'discourse.' A sermonette is a short sermon (usually associated with television broadcasting, as stations would present a sermonette before signing off for the night). The Christian Bible contains many speeches without interlocution, which some take to be sermons: Jesus' Sermon on the Mount in Matthew 5–7 (though the gospel writers do not specifically call it a sermon; the popular descriptor for Jesus' speech there came much later); and Peter after Pentecost in Acts 2:14–40 (though this speech was delivered to non-Christians and as such is not quite parallel to the popular definition of a sermon).

Western Rite Orthodoxy, also called Western Orthodoxy or the Orthodox Western Rite, are congregations within the Eastern Orthodox tradition which perform their liturgy in Western forms.

Besides altered versions of the Tridentine Mass, congregations have used Western liturgical forms such as the Sarum Rite, the Mozarabic Rite, and Gallican Rite. Some congregations use what has become known simply as the English Liturgy, which is derived from the Anglican Book of Common Prayer, albeit with some Byzantinization intended to emphasize Eastern Orthodox theological teaching. The Western Rite that exists today has been heavily influenced by the life and work of Julian Joseph Overbeck.

Ecclesiastical polity is the government of a church. There are local (congregational) forms of organization as well as denominational. A church's polity may describe its ministerial offices or an authority structure between churches. Polity relates closely to ecclesiology, the theological study of the church.