This is a notable month for fans of C.S. Lewis: He was born on Nov. 29, 1898, and left the world on the 22nd of the same month in 1963. The passing of this major figure in Christian thinking thus became a footnote to the day of President Kennedy’s assassination.

Lewis deserves to be remembered as one of the great lights of English academics for his scholarship on Medieval and Renaissance literature. But he is deservedly best known as a spokesman for Christianity. If anything, Lewis’s work is more widely read now than during...