United and uniting churches

A united church, also called a uniting church, is a denomination formed from the merger or other form of church union of two or more different Protestant Christian denominations, a number of which come from separate and distinct denominational orientations or traditions.^[1] Multi-denominationalism, or a multi-denominational church or organization, is a congregation or organization that is affiliated with two or more Christian denominations, whether they be part of the same tradition or from separate and distinct traditions.^[2][3]

Historically, unions of Protestant churches were enforced by the state, usually in order to have a stricter control over the religious sphere of its people, but also for other organizational reasons. As modern Christian ecumenism progresses, unions between various Protestant traditions are becoming more and more common,^[4] resulting in a growing number of united and uniting churches.

Examples include the United Church of Canada (1925), the Church of South India (1947), the Uniting Church in Australia (1977), the Protestant Church in the Netherlands (2004), and the United Protestant Church of France (2013).^[5][6][7][8]

Since the mid-20th century, and the rise of secularism worldwide, mainline Protestantism has shrunk.^{[9][10][11][12]} Among others, Reformed (Calvinist), Anglican, and Lutheran churches have merged, often creating large nationwide denominations.^[1] In some countries, Methodist and Congregational denominations have also merged. The phenomenon is much less common among evangelical, nondenominational and charismatic church as new ones arise and many of them remain independent of each other, although in some cases instances of evangelical church congregations joining multiple denominations in a phenomenon known as "multi-denominationalism" does occur; but in most cases Evangelicals cooperate with each other through interdenominationalism while still maintaining denominational distinctions.^[2][3]

Perhaps the oldest official united church is found in Germany, where the Protestant Church in Germany is a federation of Lutheran, United (Prussian Union) and Reformed churches, a union dating back to 1817. The first of the series of unions was at a synod in Idstein to form the Protestant Church in Hesse and Nassau in August 1817, commemorated in naming the church of Idstein Unionskirche one hundred years later.^[13][14]

Around the world, each united or uniting church comprises a different mix of predecessor Protestant denominations.^[1] Trends are visible, however, as most united and uniting churches have one or more predecessors with heritage in the Reformed tradition and many are members of the World Alliance of Reformed Churches.