John Calvin, Martin Luther's successor as the preeminent Protestant theologian, made a powerful impact on the fundamental doctrines of Protestantism.

Theologian Martin Luther forever changed Christianity when he began the Protestant Reformation in 16th-century Europe.

Blaise Pascal was a French mathematician, physicist and religious philosopher who laid the foundation for the modern theory of probabilities.

Italian Dominican theologian St. Thomas Aquinas was one of the most influential medieval thinkers of Scholasticism and the father of the Thomistic school of theology.

The sermons and writings of Jonathan Edwards helped to shape the course of Protestant theology before, during and after the Great Awakening of 1740-1742.

Albert Schweitzer was Alsatian-German theologian, philosopher, organist, and mission doctor in equatorial Africa, whose goal was the Brotherhood of Nations.

Joseph Priestley was a clergyman, political theorist, and scientist whose work advanced liberal political and religious thought and experimental chemistry.

Renaissance philosopher Count Giovanni Pico della Mirandola is remembered for writing the Oration on the Dignity of Man, a text considered to epitomize Renaissance humanism.

Cotton Mather was a Puritan minister in Boston, Massachusetts during the Colonial-era. Mather was an adviser to judges during the Salem witch trials.

Søren Kierkegaard was a 19th century Danish philosopher who wrote about Christian belief systems and helped birth existentialism.

St. Jerome was a 4th-century religious scholar and ascetic who's responsible for the Vulgate, the Catholic Church's Latin version of the Bible's Old Testament.

An influential teacher in the 19th century, theologian Mark Hopkins stressed moral values over intellectual achievement and self-education over dogmatic education.

Mary Baker Eddy was a Christian religious reformer and founder of the religious denomination known as Christian Science.

St. Catherine of Siena was a Dominican tertiary who worked to return the papacy from France to Italy. She is one of two patron saints of Italy.

Archibald Alexander was a Protestant clergyman and educator whose teachings, reviews and sermons gave him wide influence during his day.

Roman Catholic priest Gustav Gutiérrez is one of the most prominent figures in Latin American Catholicism and is considered the father of liberation theology.

Debendranath Tagore was an Indian religious reformer and Hindu philosopher.

Hashemi Rafsanjani, an ally of Ayatollah Khomeini during the Iranian Revolution, served as president of Iran from 1989 to 1997 before his defeat by Mahmoud Ahmadinejad.