Madalyn Murray O'Hair ("née" Mays; April 13, 1919 – September 29, 1995), who also used multiple pseudonyms (her most preferred being M. Bible), was an American activist, founder of American Atheists, and the organization's president from 1963 to 1986.
 She created the first issues of "American Atheist Magazine".
 One of her sons, Jon Garth Murray, became the nominal president of the organization from 1986 to 1995, but she remained "de facto" president during these nine years.
Samuel Porter Putnam (July 23, 1838 - December 11, 1896) was an American freethinker, critic and publicist.
Kay Lee Arthur (born November 11, 1933) is an international Bible teacher, four-time ECPA Christian Book Award winning author, and co-CEO of Precept Ministries International.
 Kay has systematized studying the Bible, developing a set of steps to follow so as to "mine" the details of the given book under study.
 Being systematized, it is accessible to lay persons, rather than scholars only.
 Her method has been used by thousands, being taught and utilized in small to medium-sized home study groups.
 This method does not teach anything as to what the book under study teaches, but guides the process of the student discovering what is within it.
 This method relies heavily on inductive study, the process of building the picture from the details.
 Her method of Bible study, as well as her Bible teaching, her championing of the Inductive Bible Study Method, and her national and international media broadcasts have inspired many others to study the Bible methodically.
Washington Gladden (February 11, 1836 – July 2, 1918) was a leading American Congregational pastor and early leader in the Social Gospel movement.
 He was a leading member of the Progressive Movement, serving for two years as a member of the Columbus, Ohio city council and campaigning against Boss Tweed as religious editor of the "New York Independent".
 Gladden was probably the first leading U.S. religious figure to support unionization of the workforce; he also opposed racial segregation.
 He was a prolific writer who wrote hundreds of poems, hymns, articles, editorials, and books.
The World's Sixteen Crucified Saviors; Or, Christianity Before Christ, Containing New, Startling, and Extraordinary Revelations in Religious History, which Disclose the Oriental Origin of All the Doctrines, Principles, Precepts, and Miracles of the Christian New Testament, and Furnishing a Key for Unlocking Many of Its Sacred Mysteries, Besides Comprising the History of 16 Heathen Crucified Gods is an 1875 book written by American freethinker Kersey Graves, which asserts that Jesus was not an actual person, but was a creation largely based on earlier stories of deities or god-men saviours who had been crucified and descended to and ascended from the underworld.
 Parts were reprinted in "The Book Your Church Doesn't Want You to Read" edited by Tim C. Leedom in 1994, and it was republished in its entirety in 2001.
Henry Milford Tichenor (October 23, 1858 - December 4, 1922) was a writer and magazine editor prominent in the socialist and freethinking movements during the Progressive Era and the Golden Age of Freethought of American history.
 His writings frequently condemned organized religion, Christianity in particular, as a tool used by the upper classes to maintain control over the working class.
 In the realm of opposition to religion, he has been ranked beside Clarence Darrow and Madalyn Murray O'Hair as a leading American freethinker of the twentieth century.
Robert Winsor (May 28, 1858 – January 7, 1930) was a leading American financier, investment banker, and philanthropist who, as head of the Boston investment banking firm Kidder, Peabody & Co., was at the forefront of industrial consolidation during the period leading up to the Great Depression.
 After beginning his career at Kidder, Peabody in 1880 as a lowly clerk just out of college, Winsor was quickly promoted because of his business acumen, and was held in such great esteem by the 1920s that newspaper articles would refer to him as the "J.P. Morgan of Boston" and "one of the country's leading bankers."
Rosario de Acuña Villanueva de la Iglesia, better known by the short name Rosario de Acuña and the masculine pseudonym used for her writings, Remigio Andrés Delafón (18505 May 1923) was a Spanish author of dramas, essays, short stories, and poetry.
 Born in Madrid, she wrote under the masculine pen name of Remigio Andres Delafon.
 In 1884, she became the first woman speaker in the Ateneo de Madrid.
 She was considered to be both controversial and a bold freethinker in her time.
 Her radical thinking and critique on many controversial subjects of religious dogmatism, atheistic approach, illegitimate births, civil marriage (with the eventuality of divorce) created serious controversies.
 Cited as the "first woman playwright to have a theater closed down", she died at her own home in Gijón, Asturias on 5 May 1923.
Bible Quiz, also known as Bible Bowl, is a competition between teams (often representing individual churches) over knowledge of a pre-determined section of the Bible.
 Various Protestant denominations, plus a handful of independent groups, sponsor these competitions.
 All of them take the form of a quick-recall game, similar to those used in many American schools but instead using the Bible as the subject of study and questions.
 Organizations which use the name "Bible Bowl" lean toward the format established by television's "College Bowl" in the 1950s.
 All groups feature teams competing to be the first to "buzz in" using an electronic lockout device, much like those still used in TV game shows such as "Jeopardy!" today.
Joseph Lewis (June 11, 1889 – November 4, 1968) was an American freethinker and atheist activist, publisher, and litigator.
 During the mid-twentieth century, he was one of America’s most conspicuous public atheists, the other being Emanuel Haldeman-Julius.
 Born in Montgomery, Alabama to a Jewish family, he was forced by poverty to leave school at the age of nine to find employment.
 He read avidly, becoming self-educated.
 Lewis developed his ideas from reading, among others, Robert G. Ingersoll, whose published works made him aware of Thomas Paine.
 He later credited Paine's "The Age of Reason" with helping him leave theism.

Question: Who was the leading American Freethinker born who used the pseudonym M. Bible?
Answer: Madalyn Murray O'Hair