The Anglican counter-proposal to the federalism model for unity is known as “organic union.” The word “organic” here emphasizes the body-imagery of the church, the interconnectedness of many parts but in a single whole. Naturally this relates to the episcopal requirement in Anglican understandings of the church, as in the Lambeth Quadrilateral.
The 1920 “Appeal to All Christian People” issued by the Lambeth Conference spoke of an ecumenical ideal of an “outward, visible and united society, holding one faith, having its own recognized officers, using God-given means of grace, and inspiring all its members to the worldwide service of the kingdom of God.” The historic episcopate would then be the center point of visible unity.
Needless to say, this kind of visible unity was unappealing to non-episcopal churches. To this day there has been the least success in bringing together episcopal and non-episcopal churches among all the union ventures that have taken place.
Interestingly, at the first Faith and Order meeting in 1927, the only report failing to get universal approval from the conference was the one on the unity of the church and the relations among the churches. One way or another, in the years to come the vision of organic unity has slipped from the centerstage, not least of all because it somehow seems to ask churches to stop being themselves and become something else instead, and few are willing to do that.
Even though Anglicans have been the biggest proponents of “organic unity,” most actual organizational merger has taken place between Protestant bodies. These are the “united” or “uniting” churches, mergers of previous church bodies that have decided to relinquish their old identities and take on a new one.
While there are some pre-twentieth-century united churches, such as found in the Evangelical Church of Germany (Evangelische Kirche in Deutschland), most of them have come into existence since the Second World War, and in places where colonial powers were withdrawing. In such circumstances, distinct confessional identity was nowhere near as strong as the need for common Christian witness and support. They have also tended to be among Protestants with congregationalist and presbyterian structures, though occasionally Anglicans have joined, such as in the Church of South India (though many former Anglican congregations eventually withdrew from the Church of South India).