Distinction between theological and denominational Unitarians

The term "Unitarian" has been applied both to those who hold a Unitarian theological belief and to those who belong to a Unitarian church. A hundred years ago, this would not have made much of a difference, but today it is a distinction that needs to be made. In this article, Unitarianism as a theology is referred to as simply Unitarianism, while those who belong to a Unitarian Church (and most specificially, a church that is a member of the Unitarian Universalist Association) are referred to as Unitarian Universalists.
Unitarian theology is distinguishable from the belief system of modern Unitarian and Unitarian Universalist churches and fellowships in several countries. This is because over time, some Unitarians and many Unitarian Universalists have moved away from the traditional Christian roots of Unitarianism. For example, in the 1890s the American Unitarian Association began to allow non-Christian and non-theistic churches and individuals to be part of their fellowship.
As a result, people who held no Unitarian belief began to be called "Unitarians," simply because they were members of churches that belonged to the American Unitarian Association. After several decades, the non-theistic members outnumbered the theological Unitarians.[2] A similar, though proportionally much smaller, phenomenon has taken place in the Unitarian churches in the United Kingdom, Germany, Canada, and other countries, which remain more theologically based.
The remainder of this article includes information about Unitarianism as a theology and about the development of theologically Unitarian churches in several countries around the world. For a more specific discussion of Unitarianism as it evolved into a secular liberal philosophy in the United States and elsewhere in more recent times, see Unitarian Universalism, Unitarian Universalist Association, Canadian Unitarian Council, General Assembly of Unitarian and Free Christian Churches, and International Council of Unitarians and Universalists.