C.S. Lewis and Antony Flew are two of the foremost philosophers of the 20th century. Lewis and Flew both left Christian backgrounds to become atheists during their early years of study. Later, both changed their minds accepted the existence of God. Lewis died a Christian whereas Flew died a deist. Lewis and Flew share many things in common including being accomplished academics, having multiple major worldview shifts, and changing parts of their worldviews as a result of the World Wars. Lewis and Flew both had a major influence in the development of 21st-century philosophy through a variety of works they published.