This is a list of notable converts to Christianity who were not theists before their conversion. See Nontheism for specifics of what encompasses nontheism. All names should be sourced and the source should indicate they had not been a theist, not merely non-churchgoing, before conversion.
C. E. M. Joad – English philosopher whose arguing against Christianity, from an agnostic perspective, earned him criticism from T. S. Eliot. He turned toward religion later, writing The Recovery of Belief a year before he died and returning to Christianity.
Ignace Lepp - French psychiatrist whose parents were freethinkers and who joined the Communist party at age fifteen. He broke with the party in 1937 and eventually became a Catholic priest.
Arnold Lunn – A skier, mountaineer, and writer. As an agnostic he wrote Roman Converts, which took a critical view of Catholicism and the converts to it. He later converted to Catholicism due to debating with converts, and became an apologist for the faith, although he retained a few criticisms of the faith.
Claude McKay – Bisexual Jamaican poet who went from Communist-leaning atheist to an active Catholic Christian after a stroke.
Vittorio Messori – An Italian journalist and writer called the "most translated Catholic writer in the world" by Sandro Magister. Before his conversion in 1964 he had a "perspective as a secularist and agnostic."
Sigrid Undset - Norwegian Nobel laureate who converted to Catholicism from agnosticism.
Evelyn Waugh – British novelist who converted to Catholicism from agnosticism.
John C. Wright - Science fiction author who went from atheist to Christian, specifically Catholic. Chapter 1 of the book "Atheist to Catholic: 11 Stories of Conversion", edited by Rebecca Vitz Cherico, is by him.
John Warwick Montgomery, Renowned Christian Apologist, Lutheran theologian, and barrister. As a philosophy major in college, he investigated the claims of Christianity "to preserve intellectual integrity" and converted.
Allan Sandage - a prolific Astronomer converted to Christianity later in his life stating that "I could not live a life full of cynicism. I chose to believe, and a peace of mind came over me."
A. N. Wilson – Biographer and novelist who entered the theological St Stephen's House, Oxford before proclaiming himself an atheist and writing against religion. He announced his return to Christianity in 2009.
^"Lewis lapsed into atheism in his teens but experienced a reconversion to Christianity in 1931." Lewis, C.S.. (2007). In Encyclopædia Britannica. Retrieved 28 June 2007, from Encyclopædia Britannica Online
^Interview in the National Review: FMG:You've mentioned that you now believe in God. How recent is that? Eugene Genovese: It's in the last two years. You know, in The Southern Front I still spoke as an atheist; one reviewer said that I protest too much. When the book came off the press and I had to reread it, I started wrestling with the problem philosophically, and I lost.
^Telegraph "She reacted strongly against her parents' beliefs and became a Catholic at 19, because she 'no longer found it possible to disbelieve in God.'" (pg 2)
^"...he was an atheist arguing for religious values, a man writing an essay on religion 'in a spirit of irreligion.'... He would not convert to Catholicism for two decades, but his need for religious authority was acute even in 1930." Allen Tate: Orphan of the South, p. 167, biographer Thomas A. Underwood, Princeton University Press, 2000, ISBN 0-691-06950-6
^Interview with John C. Wright at "Mostly Fiction": "For many years I had been an atheist, and a vehement, argumentative, proselytizing atheist at that. I saw no other possible option for belief for a logical thinker. My recent conversion to Christianity was a miracle, prompted by a supernatural revelation, which has satisfied my skepticism in this area, and saved my life."
^Seattle Times "In 1975, he threw off his atheism and became a Christian."
^"He converted from atheism to Christianity in his twenties after seeing how radically his patients' faith transformed their experience of suffering, and after reading several works by C. S. Lewis." The Question of God: Interview with Francis Collins, WGBH Educational Foundation, 2004 (Accessed 14 June 2007)
^[Bo Giertz, The Hammer of God,revised edition, XIII, Augsburg Fortress, Minneapolis, 2005.
^ "I knew it was Jesus immediately from the moment I started shaking. It was like he just came up and introduced himself to me. I remember him saying, “You don’t have to have this if you don’t want it.” And I said, “No, I want it.”"
^The Guardian "I grew up, and stopped being an atheist, in my 20s, in the 1980s."
^"I was brought up as an agnostic... and when I first became a Christian in the Seventies I didn't really know what it was I'd adopted." Faith in Practice: Holding on to the Mystery of Love, by Bruce Cockburn as told to Cole Morton, Third Way, September 1994, page 15. (Accessed 13 June 2007)