in Christianity, the office held by persons who are set apart by ecclesiastical authority to be ministers in the church or whose call to special vocational service in a church is afforded some measure of general recognition. The type of ministry varies in the different churches. That which developed in the early church and is retained by the Roman Catholic, Eastern Orthodox, Old Catholic, Anglican, and some Protestant churches is episcopal (see episcopacy) and is based on the three orders, or offices, of bishop, priest, and deacon.

Throughout much of the history of the Christian church, the episcopal ministry was taken for granted, but the Protestant Reformation challenged the authority of the papacy and with it the authority of the episcopal ministry.

Martin Luther (Luther, Martin) introduced the concept of the priesthood of all believers, which denied any special authority to the offices of the episcopacy. Luther (Lutheranism) intended to reassert the ministry of the whole church as a community with a mission to the world and no special restrictions on the priesthood. Ministers were encouraged to marry and were not considered a separate order in the church. Lutheran churches developed a variety of ministries, some retaining a modified episcopal form and others adopting congregational and presbyterian (Reformed and Presbyterian churches) forms.

The presbyterian form of ministry, developed by John Calvin, is used in most Presbyterian and Reformed churches (Reformed church). Ministers are teaching elders (elder) and share with lay elders and collegial regional bodies (presbyteries) (presbytery) the governance of the church.

Congregational (Congregationalism) church government, adopted by Baptists (Baptist), the United Church of Christ in the United States, and various others, accepted much of the Reformed theology but emphasized the authority of the local congregation rather than any central or regional authority.

Although historical Methodism rejected episcopacy, in the United States a modified form was developed, retaining the office of bishop and strengthening congregational influence.

Pentecostal (Pentecostalism) and evangelical (Evangelical church) groups regard charismatic gifts as the important element in ordination. Some churches (e.g., the Society of Friends (Friends, Society of)) do not have an ordained ministry.