C.S. Lewis, though considered a great apologist for the Christian faith, did not become a Christian until the age of thirty-one. The many years spent as an atheist not only influenced his writings after his conversion, but allowed him to become a great apologist.
"The Atheistic Influences of the Christian Apologist,"
Inklings Forever: Vol. 2
, Article 18.
Available at: https://pillars.taylor.edu/inklings_forever/vol2/iss1/18