A church is an association of people who share a particular belief system. The term church originated from Greek "karakion", meaning "of the lord". The term later began to replace the Greek ekklesia and Basilicae within Christendom, c. AD 300, though it was used by Christians before that time.

Origins
Many believe the Church, as described in the Bible, has a twofold character that can be described as the visible and invisible church. As the Church invisible, the church consists of all those from every time and place, who are vitally united to Christ through regeneration and salvation and who will be eternally united to Jesus Christ in eternal life. The Church visible consists of all those who visibly join themselves to a profession of faith and gathering together to know and serve the Head of the Church, Jesus Christ. The visible church exists globally in all who identify themselves as Christians and locally in particular places where believers gather for the worship of God. The visible church may also refer to an association of particular churches from multiple locations who unite themselves under a common charter and set of governmental principles. The church in the visible sense is often governed by office-bearers carrying titles such as minister, pastor, teacher, elder, and deacon.
Others make the claim that no reference to the church is ever made in the Bible that is not referring to a local visible body, such as the church in someone's house or the church as Ephesis. Those that make this claim believe that the term is sometimes used in an institutional sense in which the term refers to all of a certain type, meaning all of the local visible churches.
Church is taken by some to refer to a single, universal community, although others contend that the doctrine of the universal church was established until later. The doctrine of the universal, visible church was made explicit in the Apostles' Creed, while the less common Protestant notion of the universal, invisible church is not laid out explicitly until the Reformation. The universal church traditions generally espouse that the Church includes all who are baptized into her common faith, including the doctrines of the trinity, forgiveness of sins through the sacrificial action of Christ, and the resurrection of the body. These teachings are expressed in liturgy with the celebration of sacraments, visible signs of grace. They are passed down as the deposit of faith.
Major forms of church government include hierarchical (Roman Catholic, Anglican, Eastern Orthodoxy), presbyterian (rule by elders), and independent (Baptist, charismatic, other forms of independency).