|preceded by Modernism|
Postchristianity, postChristendom or postChristianism are variants of a term used to describe a contemporary cultural attitude closely linked to postmodernism. It may include personal world views, ideologies, religious movements or societies that are no longer rooted in the language and assumptions of Christianity, though it had previously been in an environment of ubiquitous Christianity (i.e., Christendom).
Thus defined, a post-Christian world is one where Christianity is no longer the dominant civil religion, but one that has, gradually over extended periods of time, assumed values, culture, and worldviews that are not necessarily Christian (and further may not necessarily reflect any world religion's standpoint). This situation applies to much of Europe, in particular in Central and Northern Europe, where no more than half of the residents in those lands profess belief in a transcendent, personal and monotheistically-conceived deity.
In his 1961 The Death of God, the French theologian Gabriel Vahanian argued that modern secular culture in most of Western Civilization had lost all sense of the sacred, lacked any sacramental meaning, and disdained any transcendental purpose or sense of providence, bringing him to the conclusion that for the modern mind, "God is dead".
Other thinkers, namely Thomas J. J. Altizer and William Hamilton, two theologians on the faculty of Emory University, drawing upon sources dating back to some of the aphorisms in Dietrich Bonhoeffer's Letters and Papers from Prison, would bring this line of thought to public attention in a short-lived intellectual fad that occurred in the mid-to-late-1960s among some younger Protestant theologians and ministerial students. Conservative reaction on the right and social advocacy efforts on the left blunted its impact, however, and it quickly became forgotten in favor of more ethically-oriented movements such as liberation and feminist theologies, within the Protestant mainline at least.
Some American Christians (primarily Protestants) also use this term to discuss evangelism to unchurched individuals who may have grown up in a non-Christian culture where such traditional Biblical references may be unfamiliar concepts. The argument goes that in previous generations in the United States, such concept and other artifacts of Christianese would have been common cultural knowledge and would not have needed to be taught to adult converts to Christianity. In this sense, post-Christian is not a negative term, but is used to describe the special remediative care that would be needed to introduce new Christians to the nuances of Christian life and practice.
Some groups, mainly liberal or radical ones, even use the term "post-Christian" as a self-description, not regarding it as an epithet whatsoever. Dana McLean Greeley, the first president of the Unitarian Universalist Association, described Unitarian Universalism as postchristian insofar as Christians no longer considered it Christian, while persons of other religions would likely describe it as Christian, as least historically. 
- Christian atheism
- Christian existentialism
- John Shelby Spong
- Postmodern Christianity
- Liberal Religion in the Post Christian Era, Edward A. Cahill, 1974
- The Post Christian Mind: Exposing Its Destructive Agenda, Harry Blamires, Vine, 1999 (ISBN 1-56955-142-1).
- "The Death of God: The Culture of Our Post-Christian Era", Gabriel Vahanian, George Braziller, NY, 1961
- Dana MacLean Greeley, 25 Beacon Street, and Other Recollections (Boston: Beacon Press, 1971), pp. 11-12.
- Thomas J. J. Altizer, The Gospel of Christian Atheism (Philadelphia: Westminster, 1966).
- Thomas J. J. Altizer and William Hamilton, Radical Theology and the Death of God (Indianapolis: Bobbs-Merrill, 1966).
- Bernard Murchland, ed., The Meaning of the Death of God (New York: Random House, 1967)