Church union

One of the first of these occurred in 1817, when Lutheran and Reformed churches in Prussia merged into the Prussian Union.

[4] In the twentieth century many churches merged as a result of the Ecumenical movement.

[6] The structure was similar to the Federation which formed the Commonwealth of Australia on January 1 of that same year.

In his inaugural moderatorial address, John Meiklejohn made it clear that the ecclesiastical union consciously reflected the political union of the Australian colonies: "We have, by forming this Assembly, formed a Court whose jurisdiction is, as regards territory, equal to, and coterminous with that of the Federal Parliament, and like it, is representative in its character."

The term "union" (e.g., the Union of Brest of 1596) is also used for the arrangement when a group of Orthodox Christians enters communion with the Catholic Church's Pope of Rome, while wishing to maintain their Eastern rites.